libexpat before 2.8.2 lacks handler call depth tracking for calls to XML_ResumeParser from within handlers in cases of a policy violation. Thus, a use-after-free can occur (similar to the CVE-2026-50219 situation).

According to the versions of the expat packages installed, the EulerOS installation on the remote host is affected by the following vulnerabilities :

    libexpat before 2.8.2 lacks handler call depth tracking for calls to XML_ResumeParser from within handlers     in cases of a policy violation. Thus, a use-after-free can occur (similar to the CVE-2026-50219     situation).(CVE-2026-56131)

    libexpat before 2.8.2 has an integer overflow in addBinding.(CVE-2026-56404)

    xmlwf in libexpat before 2.8.2 has an integer overflow in endDoctypeDecl via NOTATION     declarations.(CVE-2026-56411)

    xmlwf in libexpat before 2.8.2 has an integer overflow in resolveSystemId.(CVE-2026-56410)

    libexpat before 2.8.2 has an integer overflow in storeAtts.(CVE-2026-56403)

    libexpat before 2.8.2 does not consider XML_TOK_DATA_CHARS in doCdataSection and thus lacks handler call     depth tracking for various calls from within handlers in cases of a policy violation. Thus, a use-after-     free can occur. NOTE: this issue exists because of an incomplete fix for CVE-2026-50219.(CVE-2026-56412)

    libexpat before 2.8.2 has an integer overflow in doProlog that is related to storeEntityValue and entity     textLen.(CVE-2026-56407)

    libexpat before 2.8.2 has an integer overflow in XML_ParseBuffer because it lacked a check that was     present in XML_Parse.(CVE-2026-56406)

    libexpat before 2.8.2 has an integer overflow in getAttributeId.(CVE-2026-56405)

    libexpat before 2.8.2 lacks handler call depth tracking for calls to XML_GetBuffer, XML_Parse,     XML_ParseBuffer, XML_ParserFree, or XML_ParserReset from within handlers in cases of a policy violation.
    Thus, a use-after-free can occur,(CVE-2026-50219)

    xmlwf in libexpat before 2.8.2 has an integer overflow for the output filename when -d outputDir is     used.(CVE-2026-56409)

    libexpat before 2.8.2 has an integer overflow in copyString.(CVE-2026-56408)

    In libexpat before 2.8.2, there is a heap-based buffer overflow in doProlog in xmlparse.c because scaffold     backing array reallocation is mishandled when there is data-structure sharing across     parsers.(CVE-2026-56132)

Tenable has extracted the preceding description block directly from the EulerOS expat security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Debian 12 host has packages installed that are affected by multiple vulnerabilities as referenced in the dla-4765 advisory.

    - -------------------------------------------------------------------------     Debian LTS Advisory DLA-4765-1                debian-lts@lists.debian.org     https://www.debian.org/lts/security/                       Andrej Shadura     August 31, 2026                               https://wiki.debian.org/LTS
    - -------------------------------------------------------------------------

    Package        : expat     Version        : 2.5.0-1+deb12u3     CVE ID         : CVE-2026-50219 CVE-2026-56131 CVE-2026-56403                      CVE-2026-56404 CVE-2026-56405 CVE-2026-56406                      CVE-2026-56407 CVE-2026-56408 CVE-2026-56409                      CVE-2026-56410 CVE-2026-56411 CVE-2026-56412                      CVE-2026-72522 CVE-2026-76957

    CVE-2026-50219, CVE-2026-56131, CVE-2026-76957

        Calling certain libexpat functions from within a handler could cause         use-after-free.

    CVE-2026-56403, CVE-2026-56404, CVE-2026-56405, CVE-2026-56406,     CVE-2026-56407, CVE-2026-56408, CVE-2026-56409, CVE-2026-56410,     CVE-2026-56411

        Integer overflow in several functions.

    CVE-2026-56412

        A missing reentrancy guard around CDATA section handler calls could         cause use-after-free.

    CVE-2026-72522

        An out-of-bounds read in expat's internal UTF-16 conversion functions         could cause an infinite loop when processing crafted input, resulting         in a denial of service.

    For Debian 12 bookworm, these problems have been fixed in version     2.5.0-1+deb12u3.

    We recommend that you upgrade your expat packages.

    For the detailed security status of expat please refer to     its security tracker page at:
    https://security-tracker.debian.org/tracker/expat

    Further information about Debian LTS security advisories, how to apply     these updates to your system and frequently asked questions can be     found at: https://wiki.debian.org/LTS

Tenable has extracted the preceding description block directly from the Debian security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The Unity Linux 20 host has a package installed that is affected by a vulnerability as referenced in the UTSA-2026-099458 advisory.

    libexpat before 2.8.2 lacks handler call depth tracking for calls to XML_ResumeParser from within handlers     in cases of a policy violation. Thus, a use-after-free can occur (similar to the CVE-2026-50219     situation).

Tenable has extracted the preceding description block directly from the Unity Linux security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Debian 13 host has packages installed that are affected by multiple vulnerabilities as referenced in the dsa-6404 advisory.

    - -------------------------------------------------------------------------     Debian Security Advisory DSA-6404-1                   security@debian.org     https://www.debian.org/security/                                  Aron Xu     July 30, 2026                         https://www.debian.org/security/faq
    - -------------------------------------------------------------------------

    Package        : expat     CVE ID         : CVE-2025-59375 CVE-2026-24515 CVE-2026-25210 CVE-2026-32776                      CVE-2026-32777 CVE-2026-32778 CVE-2026-41080 CVE-2026-45186                      CVE-2026-50219 CVE-2026-56131 CVE-2026-56132 CVE-2026-56403                      CVE-2026-56404 CVE-2026-56405 CVE-2026-56406 CVE-2026-56407                      CVE-2026-56408 CVE-2026-56409 CVE-2026-56410 CVE-2026-56411                      CVE-2026-56412

    Multiple security issues were discovered in expat, an XML parsing C library,     including integer overflows, out-of-bounds write, NULL pointer dereferences,     excessive resource consumption, and memory corruption through re-entrant     parser API calls, which may result in denial of service or potentially the     execution of arbitrary code.

    For the stable distribution (trixie), this problem has been fixed in     version 2.8.2-1~deb13u1.

    We recommend that you upgrade your expat packages.

    For the detailed security status of expat please refer to     its security tracker page at:
    https://security-tracker.debian.org/tracker/expat

    Further information about Debian Security Advisories, how to apply     these updates to your system and frequently asked questions can be     found at: https://www.debian.org/security/

    Mailing list: debian-security-announce@lists.debian.org

Tenable has extracted the preceding description block directly from the Debian security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2023-2026-1928 advisory.

    Privilege escalation in the Graphics: WebRender component. This vulnerability was fixed in Firefox 152,     Firefox ESR 140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12289)

    Memory safety bug fixed in Thunderbird 152. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12290)

    Use-after-free in the Networking: HTTP component. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12291)

    Incorrect boundary conditions in the Web Audio component. This vulnerability was fixed in Firefox 152,     Firefox ESR 140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12292)

    Sandbox escape in the DOM: Workers component. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12294)

    Sandbox escape in the DOM: Navigation component. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12295)

    Sandbox escape in the Security: Process Sandboxing component. This vulnerability was fixed in Firefox 152,     Firefox ESR 140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12296)

    Sandbox escape due to incorrect boundary conditions in the Networking component. This vulnerability was     fixed in Firefox 152, Firefox ESR 140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12.
    (CVE-2026-12297)

    Memory safety bug fixed in Thunderbird 152. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12298)

    JIT miscompilation in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 152, Firefox     ESR 140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12299)

    Mitigation bypass in the DOM: Security component. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12302)

    Same-origin policy bypass in the Networking: Cookies component. This vulnerability was fixed in Firefox     152, Firefox ESR 140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12304)

    Memory safety bug fixed in Thunderbird 152. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12305)

    Memory safety bug fixed in Thunderbird 152. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12306)

    Memory safety bug fixed in Thunderbird 152. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12307)

    Memory safety bug fixed in Thunderbird 152. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12308)

    Memory safety bug fixed in Thunderbird 152. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12309)

    Memory safety bug fixed in Thunderbird 152. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12310)

    Information disclosure, sandbox escape in the Security: Process Sandboxing component. This vulnerability     was fixed in Firefox 152, Firefox ESR 140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12311)

    Memory safety bug fixed in Thunderbird 152. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12312)

    Information disclosure, sandbox escape in the Security: Process Sandboxing component. This vulnerability     was fixed in Firefox 152, Firefox ESR 140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12313)

    Memory safety bug fixed in Thunderbird 152. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12314)

    Mitigation bypass in the DOM: Security component. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12315)

    Incorrect boundary conditions in the Graphics: CanvasWebGL component. This vulnerability was fixed in     Firefox 152, Firefox ESR 140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12324)

    Denial-of-service in the Graphics: ImageLib component. This vulnerability was fixed in Firefox 152,     Firefox ESR 140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12325)

    Memory safety bugs present in Firefox ESR 140.11, Thunderbird ESR 140.11, Firefox 151 and Thunderbird 151.
    Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of     these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 152,     Firefox ESR 140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12327)

    Memory safety bugs present in Firefox ESR 115.36, Firefox ESR 140.11, Thunderbird ESR 140.11, Firefox 151     and Thunderbird 151. Some of these bugs showed evidence of memory corruption and we presume that with     enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed     in Firefox 152, Firefox ESR 140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12.
    (CVE-2026-12328)

    Memory safety bug fixed in Thunderbird ESR 140.12. This vulnerability was fixed in Firefox ESR 140.12 and     Thunderbird 140.12. (CVE-2026-12329)

    Incorrect boundary conditions in the Internationalization component. This vulnerability was fixed in     Firefox ESR 140.12, Firefox ESR 115.37, and Thunderbird 140.12. (CVE-2026-12330)

    libexpat before 2.8.2 lacks handler call depth tracking for calls to XML_GetBuffer, XML_Parse,     XML_ParseBuffer, XML_ParserFree, or XML_ParserReset from within handlers in cases of a policy violation.
    Thus, a use-after-free can occur, (CVE-2026-50219)

    libexpat before 2.8.2 lacks handler call depth tracking for calls to XML_ResumeParser from within handlers     in cases of a policy violation. Thus, a use-after-free can occur (similar to the CVE-2026-50219     situation). (CVE-2026-56131)

    In libexpat before 2.8.2, there is a heap-based buffer overflow in doProlog in xmlparse.c because scaffold     backing array reallocation is mishandled when there is data-structure sharing across parsers.
    (CVE-2026-56132)

    A heap buffer overflow vulnerability was found in libaom, the reference AV1 codec implementation. A flaw     in the AV1 encoder's Look-Ahead Processing (LAP) mode causes the first-pass stats ring buffer wrap-around     guard to be bypassed when g_lag_in_frames is set to 1 or higher. This results in a 232-byte out-of-bounds     write on every encoded frame after the second, corrupting adjacent heap objects. An attacker who can     influence encoder configuration in a transcoding service or WebRTC session could exploit this to cause a     denial of service (process crash) or potentially achieve code execution. (CVE-2026-56208)

    A heap-buffer-overflow read vulnerability was found in libaom, the reference AV1 codec implementation. A     missing bounds check in the SVC (Scalable Video Coding) layer ID control function allows setting a     spatial_layer_id exceeding the configured number of layers. This causes an out-of-bounds heap read of     approximately 40,728 bytes when computing a layer context array index. An attacker who can influence SVC     encoder parameters in a network-facing service could exploit this for information disclosure (heap content     leak) or denial of service (segmentation fault from hitting unmapped memory). (CVE-2026-56210)

    A remote code execution vulnerability was found in libaom, the reference AV1 codec implementation.
    Insufficient bounds validation in the AV1 encoder's SVC (Scalable Video Coding) layer ID control allows an     attacker to supply crafted video frame pixels that overlap with internal encoder layer context structures.
    In fork-based video processing services, an attacker can use this to hijack the cyclic refresh map     pointer, brute-force the process base address via a crash oracle, and redirect control flow to achieve     arbitrary command execution. Exploitation requires the target service to use libaom with SVC encoding     enabled and accept attacker-supplied video frames. (CVE-2026-56211)

    libexpat before 2.8.2 has an integer overflow in storeAtts. (CVE-2026-56403)

    libexpat before 2.8.2 has an integer overflow in addBinding. (CVE-2026-56404)

    libexpat before 2.8.2 has an integer overflow in getAttributeId. (CVE-2026-56405)

    libexpat before 2.8.2 has an integer overflow in XML_ParseBuffer because it lacked a check that was     present in XML_Parse. (CVE-2026-56406)

    libexpat before 2.8.2 has an integer overflow in doProlog that is related to storeEntityValue and entity     textLen. (CVE-2026-56407)

    libexpat before 2.8.2 has an integer overflow in copyString. (CVE-2026-56408)

    libexpat before 2.8.2 does not consider XML_TOK_DATA_CHARS in doCdataSection and thus lacks handler call     depth tracking for various calls from within handlers in cases of a policy violation. Thus, a use-after-     free can occur. NOTE: this issue exists because of an incomplete fix for CVE-2026-50219. (CVE-2026-56412)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The version of firefox installed on the remote host is prior to 140.12.0-1. It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2FIREFOX-2026-062 advisory.

    Privilege escalation in the Graphics: WebRender component. This vulnerability was fixed in Firefox 152,     Firefox ESR 140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12289)

    Memory safety bug fixed in Thunderbird 152. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12290)

    Use-after-free in the Networking: HTTP component. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12291)

    Incorrect boundary conditions in the Web Audio component. This vulnerability was fixed in Firefox 152,     Firefox ESR 140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12292)

    Sandbox escape in the DOM: Workers component. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12294)

    Sandbox escape in the DOM: Navigation component. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12295)

    Sandbox escape in the Security: Process Sandboxing component. This vulnerability was fixed in Firefox 152,     Firefox ESR 140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12296)

    Sandbox escape due to incorrect boundary conditions in the Networking component. This vulnerability was     fixed in Firefox 152, Firefox ESR 140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12.
    (CVE-2026-12297)

    Memory safety bug fixed in Thunderbird 152. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12298)

    JIT miscompilation in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 152, Firefox     ESR 140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12299)

    Mitigation bypass in the DOM: Security component. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12302)

    Same-origin policy bypass in the Networking: Cookies component. This vulnerability was fixed in Firefox     152, Firefox ESR 140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12304)

    Memory safety bug fixed in Thunderbird 152. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12305)

    Memory safety bug fixed in Thunderbird 152. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12306)

    Memory safety bug fixed in Thunderbird 152. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12307)

    Memory safety bug fixed in Thunderbird 152. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12308)

    Memory safety bug fixed in Thunderbird 152. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12309)

    Memory safety bug fixed in Thunderbird 152. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12310)

    Information disclosure, sandbox escape in the Security: Process Sandboxing component. This vulnerability     was fixed in Firefox 152, Firefox ESR 140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12311)

    Memory safety bug fixed in Thunderbird 152. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12312)

    Information disclosure, sandbox escape in the Security: Process Sandboxing component. This vulnerability     was fixed in Firefox 152, Firefox ESR 140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12313)

    Memory safety bug fixed in Thunderbird 152. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12314)

    Mitigation bypass in the DOM: Security component. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12315)

    Incorrect boundary conditions in the Graphics: CanvasWebGL component. This vulnerability was fixed in     Firefox 152, Firefox ESR 140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12324)

    Denial-of-service in the Graphics: ImageLib component. This vulnerability was fixed in Firefox 152,     Firefox ESR 140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12325)

    Memory safety bugs present in Firefox ESR 140.11, Thunderbird ESR 140.11, Firefox 151 and Thunderbird 151.
    Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of     these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 152,     Firefox ESR 140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12327)

    Memory safety bugs present in Firefox ESR 115.36, Firefox ESR 140.11, Thunderbird ESR 140.11, Firefox 151     and Thunderbird 151. Some of these bugs showed evidence of memory corruption and we presume that with     enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed     in Firefox 152, Firefox ESR 140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12.
    (CVE-2026-12328)

    Memory safety bug fixed in Thunderbird ESR 140.12. This vulnerability was fixed in Firefox ESR 140.12 and     Thunderbird 140.12. (CVE-2026-12329)

    Incorrect boundary conditions in the Internationalization component. This vulnerability was fixed in     Firefox ESR 140.12, Firefox ESR 115.37, and Thunderbird 140.12. (CVE-2026-12330)

    libexpat before 2.8.2 lacks handler call depth tracking for calls to XML_GetBuffer, XML_Parse,     XML_ParseBuffer, XML_ParserFree, or XML_ParserReset from within handlers in cases of a policy violation.
    Thus, a use-after-free can occur, (CVE-2026-50219)

    libexpat before 2.8.2 lacks handler call depth tracking for calls to XML_ResumeParser from within handlers     in cases of a policy violation. Thus, a use-after-free can occur (similar to the CVE-2026-50219     situation). (CVE-2026-56131)

    In libexpat before 2.8.2, there is a heap-based buffer overflow in doProlog in xmlparse.c because scaffold     backing array reallocation is mishandled when there is data-structure sharing across parsers.
    (CVE-2026-56132)

    A heap buffer overflow vulnerability was found in libaom, the reference AV1 codec implementation. A flaw     in the AV1 encoder's Look-Ahead Processing (LAP) mode causes the first-pass stats ring buffer wrap-around     guard to be bypassed when g_lag_in_frames is set to 1 or higher. This results in a 232-byte out-of-bounds     write on every encoded frame after the second, corrupting adjacent heap objects. An attacker who can     influence encoder configuration in a transcoding service or WebRTC session could exploit this to cause a     denial of service (process crash) or potentially achieve code execution. (CVE-2026-56208)

    A heap-buffer-overflow read vulnerability was found in libaom, the reference AV1 codec implementation. A     missing bounds check in the SVC (Scalable Video Coding) layer ID control function allows setting a     spatial_layer_id exceeding the configured number of layers. This causes an out-of-bounds heap read of     approximately 40,728 bytes when computing a layer context array index. An attacker who can influence SVC     encoder parameters in a network-facing service could exploit this for information disclosure (heap content     leak) or denial of service (segmentation fault from hitting unmapped memory). (CVE-2026-56210)

    A remote code execution vulnerability was found in libaom, the reference AV1 codec implementation.
    Insufficient bounds validation in the AV1 encoder's SVC (Scalable Video Coding) layer ID control allows an     attacker to supply crafted video frame pixels that overlap with internal encoder layer context structures.
    In fork-based video processing services, an attacker can use this to hijack the cyclic refresh map     pointer, brute-force the process base address via a crash oracle, and redirect control flow to achieve     arbitrary command execution. Exploitation requires the target service to use libaom with SVC encoding     enabled and accept attacker-supplied video frames. (CVE-2026-56211)

    libexpat before 2.8.2 has an integer overflow in storeAtts. (CVE-2026-56403)

    libexpat before 2.8.2 has an integer overflow in addBinding. (CVE-2026-56404)

    libexpat before 2.8.2 has an integer overflow in getAttributeId. (CVE-2026-56405)

    libexpat before 2.8.2 has an integer overflow in XML_ParseBuffer because it lacked a check that was     present in XML_Parse. (CVE-2026-56406)

    libexpat before 2.8.2 has an integer overflow in doProlog that is related to storeEntityValue and entity     textLen. (CVE-2026-56407)

    libexpat before 2.8.2 has an integer overflow in copyString. (CVE-2026-56408)

    libexpat before 2.8.2 does not consider XML_TOK_DATA_CHARS in doCdataSection and thus lacks handler call     depth tracking for various calls from within handlers in cases of a policy violation. Thus, a use-after-     free can occur. NOTE: this issue exists because of an incomplete fix for CVE-2026-50219. (CVE-2026-56412)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The version of thunderbird installed on the remote host is prior to 140.12.0-1. It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2-2026-3795 advisory.

    Privilege escalation in the Graphics: WebRender component. This vulnerability was fixed in Firefox 152,     Firefox ESR 140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12289)

    Memory safety bug fixed in Thunderbird 152. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12290)

    Incorrect boundary conditions in the Web Audio component. This vulnerability was fixed in Firefox 152,     Firefox ESR 140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12292)

    Sandbox escape in the DOM: Workers component. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12294)

    Sandbox escape in the DOM: Navigation component. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12295)

    Sandbox escape in the Security: Process Sandboxing component. This vulnerability was fixed in Firefox 152,     Firefox ESR 140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12296)

    Sandbox escape due to incorrect boundary conditions in the Networking component. This vulnerability was     fixed in Firefox 152, Firefox ESR 140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12.
    (CVE-2026-12297)

    Memory safety bug fixed in Thunderbird 152. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12298)

    JIT miscompilation in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 152, Firefox     ESR 140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12299)

    Same-origin policy bypass in the Networking: Cookies component. This vulnerability was fixed in Firefox     152, Firefox ESR 140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12304)

    Memory safety bug fixed in Thunderbird 152. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12305)

    Memory safety bug fixed in Thunderbird 152. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12306)

    Memory safety bug fixed in Thunderbird 152. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12307)

    Memory safety bug fixed in Thunderbird 152. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12308)

    Memory safety bug fixed in Thunderbird 152. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12309)

    Memory safety bug fixed in Thunderbird 152. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12310)

    Memory safety bug fixed in Thunderbird 152. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12312)

    Information disclosure, sandbox escape in the Security: Process Sandboxing component. This vulnerability     was fixed in Firefox 152, Firefox ESR 140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12313)

    Memory safety bug fixed in Thunderbird 152. This vulnerability was fixed in Firefox 152, Firefox ESR     140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12314)

    Incorrect boundary conditions in the Graphics: CanvasWebGL component. This vulnerability was fixed in     Firefox 152, Firefox ESR 140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12324)

    Denial-of-service in the Graphics: ImageLib component. This vulnerability was fixed in Firefox 152,     Firefox ESR 140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12325)

    Memory safety bugs present in Firefox ESR 140.11, Thunderbird ESR 140.11, Firefox 151 and Thunderbird 151.
    Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of     these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 152,     Firefox ESR 140.12, Thunderbird 152, and Thunderbird 140.12. (CVE-2026-12327)

    Memory safety bugs present in Firefox ESR 115.36, Firefox ESR 140.11, Thunderbird ESR 140.11, Firefox 151     and Thunderbird 151. Some of these bugs showed evidence of memory corruption and we presume that with     enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed     in Firefox 152, Firefox ESR 140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12.
    (CVE-2026-12328)

    Memory safety bug fixed in Thunderbird ESR 140.12. This vulnerability was fixed in Firefox ESR 140.12 and     Thunderbird 140.12. (CVE-2026-12329)

    Incorrect boundary conditions in the Internationalization component. This vulnerability was fixed in     Firefox ESR 140.12, Firefox ESR 115.37, and Thunderbird 140.12. (CVE-2026-12330)

    libexpat before 2.8.2 lacks handler call depth tracking for calls to XML_GetBuffer, XML_Parse,     XML_ParseBuffer, XML_ParserFree, or XML_ParserReset from within handlers in cases of a policy violation.
    Thus, a use-after-free can occur, (CVE-2026-50219)

    libexpat before 2.8.2 lacks handler call depth tracking for calls to XML_ResumeParser from within handlers     in cases of a policy violation. Thus, a use-after-free can occur (similar to the CVE-2026-50219     situation). (CVE-2026-56131)

    In libexpat before 2.8.2, there is a heap-based buffer overflow in doProlog in xmlparse.c because scaffold     backing array reallocation is mishandled when there is data-structure sharing across parsers.
    (CVE-2026-56132)

    A heap buffer overflow vulnerability was found in libaom, the reference AV1 codec implementation. A flaw     in the AV1 encoder's Look-Ahead Processing (LAP) mode causes the first-pass stats ring buffer wrap-around     guard to be bypassed when g_lag_in_frames is set to 1 or higher. This results in a 232-byte out-of-bounds     write on every encoded frame after the second, corrupting adjacent heap objects. An attacker who can     influence encoder configuration in a transcoding service or WebRTC session could exploit this to cause a     denial of service (process crash) or potentially achieve code execution. (CVE-2026-56208)

    A heap-buffer-overflow read vulnerability was found in libaom, the reference AV1 codec implementation. A     missing bounds check in the SVC (Scalable Video Coding) layer ID control function allows setting a     spatial_layer_id exceeding the configured number of layers. This causes an out-of-bounds heap read of     approximately 40,728 bytes when computing a layer context array index. An attacker who can influence SVC     encoder parameters in a network-facing service could exploit this for information disclosure (heap content     leak) or denial of service (segmentation fault from hitting unmapped memory). (CVE-2026-56210)

    A remote code execution vulnerability was found in libaom, the reference AV1 codec implementation.
    Insufficient bounds validation in the AV1 encoder's SVC (Scalable Video Coding) layer ID control allows an     attacker to supply crafted video frame pixels that overlap with internal encoder layer context structures.
    In fork-based video processing services, an attacker can use this to hijack the cyclic refresh map     pointer, brute-force the process base address via a crash oracle, and redirect control flow to achieve     arbitrary command execution. Exploitation requires the target service to use libaom with SVC encoding     enabled and accept attacker-supplied video frames. (CVE-2026-56211)

    libexpat before 2.8.2 has an integer overflow in storeAtts. (CVE-2026-56403)

    libexpat before 2.8.2 has an integer overflow in addBinding. (CVE-2026-56404)

    libexpat before 2.8.2 has an integer overflow in getAttributeId. (CVE-2026-56405)

    libexpat before 2.8.2 has an integer overflow in XML_ParseBuffer because it lacked a check that was     present in XML_Parse. (CVE-2026-56406)

    libexpat before 2.8.2 has an integer overflow in doProlog that is related to storeEntityValue and entity     textLen. (CVE-2026-56407)

    libexpat before 2.8.2 has an integer overflow in copyString. (CVE-2026-56408)

    libexpat before 2.8.2 does not consider XML_TOK_DATA_CHARS in doCdataSection and thus lacks handler call     depth tracking for various calls from within handlers in cases of a policy violation. Thus, a use-after-     free can occur. NOTE: this issue exists because of an incomplete fix for CVE-2026-50219. (CVE-2026-56412)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

There are packages installed that are affected by multiple vulnerabilities referenced in the following CVEs:

  - libexpat before 2.8.2 does not consider XML_TOK_DATA_CHARS in doCdataSection and thus lacks handler call
    depth tracking for various calls from within handlers in cases of a policy violation. Thus, a use-after-
    free can occur. NOTE: this issue exists because of an incomplete fix for CVE-2026-50219. (CVE-2026-56412)

  - libexpat before 2.8.2 lacks handler call depth tracking for calls to XML_GetBuffer, XML_Parse,
    XML_ParseBuffer, XML_ParserFree, or XML_ParserReset from within handlers in cases of a policy violation.
    Thus, a use-after-free can occur, (CVE-2026-50219)

  - libexpat before 2.8.2 lacks handler call depth tracking for calls to XML_ResumeParser from within handlers
    in cases of a policy violation. Thus, a use-after-free can occur (similar to the CVE-2026-50219
    situation). (CVE-2026-56131)

  - In libexpat before 2.8.2, there is a heap-based buffer overflow in doProlog in xmlparse.c because scaffold
    backing array reallocation is mishandled when there is data-structure sharing across parsers.
    (CVE-2026-56132)

  - libexpat before 2.8.2 has an integer overflow in storeAtts. (CVE-2026-56403)

The version of FreeBSD installed on the remote host is prior to tested version. It is, therefore, affected by multiple vulnerabilities as referenced in the d06b1fa2-731f-11f1-a0d2-589cfc10a551 advisory.

    Expat 2.8.2 was released yesterday. The key motivation for cutting a release and doing so now was     getting security and non-security bugsfixes out to users. On the security side,     13 vulnerabilities have been fixed:

Tenable has extracted the preceding description block directly from the FreeBSD security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - libexpat before 2.8.2 lacks handler call depth tracking for calls to XML_ResumeParser from within handlers     in cases of a policy violation. Thus, a use-after-free can occur (similar to the CVE-2026-50219     situation). (CVE-2026-56131)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Type	Severity
343660	EulerOS 2.0 SP12 : expat (EulerOS-SA-2026-3333)	Nessus	Huawei Local Security Checks	Local	medium
343618	EulerOS 2.0 SP12 : expat (EulerOS-SA-2026-3258)	Nessus	Huawei Local Security Checks	Local	medium
341830	Debian dla-4765 : expat - security update	Nessus	Debian Local Security Checks	Local	high
336022	Unity Linux 20.1070e Security Update: expat (UTSA-2026-099458)	Nessus	Unity Linux Local Security Checks	Local	medium
330837	Debian dsa-6404 : expat - security update	Nessus	Debian Local Security Checks	Local	high
327385	Amazon Linux 2023 : firefox (ALAS2023-2026-1928)	Nessus	Amazon Linux Local Security Checks	Local	medium
325581	Amazon Linux 2 : firefox, --advisory ALAS2FIREFOX-2026-062 (ALASFIREFOX-2026-062)	Nessus	Amazon Linux Local Security Checks	Local	medium
325578	Amazon Linux 2 : thunderbird, --advisory ALAS2-2026-3795 (ALAS-2026-3795)	Nessus	Amazon Linux Local Security Checks	Local	medium
444103	Alpine: libexpat, multiple expat packages: security update to 2.8.2-r0	Tenable Cloud Security	Alpine Linux Local Security Checks	Local	medium
444103	Alpine: libexpat, multiple expat packages: security update to 2.8.2-r0	Tenable Self-Hosted Container Security	Alpine Linux Local Security Checks	Local	medium
323688	FreeBSD : Multiple vulnerability found in Expat (d06b1fa2-731f-11f1-a0d2-589cfc10a551)	Nessus	FreeBSD Local Security Checks	Local	medium
321769	Linux Distros Unpatched Vulnerability : CVE-2026-56131	Nessus	Misc.	Local	medium

Detections

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CVE-2026-56131

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