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

  - Expat through 2.8.3 contains a denial of service vulnerability caused by quadratic algorithmic complexity
    in the storeAtts() function in xmlparse.c, where processing N specified attributes with non-normalized
    values triggers an O(N^2) linear scan of elementType->defaultAtts to determine CDATA status. A remote
    unauthenticated attacker can supply a single well-formed XML document of a few megabytes to an application
    parsing untrusted XML to cause excessive CPU consumption, resulting in denial of service without requiring
    authentication, external entity resolution, or non-default parser options. (CVE-2026-66046)

  - Expat through 2.8.3 contains an out-of-bounds read vulnerability that allows attackers to trigger memory
    corruption by processing XML with external entity parsers created via XML_ExternalEntityParserCreate. A
    struct size mismatch between ELEMENT_TYPE members causes storeAtts to read the attIndex member past
    allocated memory boundaries, resulting in failure to normalize whitespace in non-CDATA attributes or a
    wild pointer dereference causing a segfault. This vulnerability was introduced by the fix for
    CVE-2026-66046. (CVE-2026-76641)

  - In libexpat 2.8.2 and 2.8.3 before 2.8.4, misinterpretation of getentropy's return code leads to
    insufficient entropy, which results in being vulnerable to hash flooding attacks, causing a denial of
    service via crafted XML content. (CVE-2026-76956)

  - libexpat before 2.8.4 lacks handler call depth tracking with custom encoding callbacks. Thus, a use-after-
    free can occur. NOTE: this is similar to CVE-2026-50219, CVE-2026-56131 and CVE-2026-56412.
    (CVE-2026-76957)

The version of firefox installed on the remote host is prior to 140.14.0-1. It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2FIREFOX-2026-064 advisory.

    Expat through 2.8.3 contains a denial of service vulnerability caused by quadratic algorithmic complexity     in the storeAtts() function in xmlparse.c, where processing N specified attributes with non-normalized     values triggers an O(N^2) linear scan of elementType->defaultAtts to determine CDATA status. A remote     unauthenticated attacker can supply a single well-formed XML document of a few megabytes to an application     parsing untrusted XML to cause excessive CPU consumption, resulting in denial of service without requiring     authentication, external entity resolution, or non-default parser options. (CVE-2026-66046)

    libexpat before 2.8.3 has an out-of-bounds read and resultant infinite loop because low surrogates are     treated the same as high surrogates during Unicode processing in the *_toUtf16 functions. (CVE-2026-72522)

    Site isolation issue in the Graphics: CanvasWebGL component. This vulnerability was fixed in Firefox 154,     Firefox ESR 115.39, Firefox ESR 140.14, and Firefox ESR 153.1. (CVE-2026-74934)

    Privilege escalation in the DOM: Networking component. This vulnerability was fixed in Firefox 154,     Firefox ESR 115.39, Firefox ESR 140.14, and Firefox ESR 153.1. (CVE-2026-74935)

    Use-after-free in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox 154,     Firefox ESR 140.14, and Firefox ESR 153.1. (CVE-2026-74936)

    Mitigation bypass in the JavaScript: GC component. This vulnerability was fixed in Firefox 154, Firefox     ESR 153.1, Thunderbird 154, and Thunderbird 153.1. (CVE-2026-74938)

    Privilege escalation in the DOM: Navigation component. This vulnerability was fixed in Firefox 154,     Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and     Thunderbird 153.1. (CVE-2026-74939)

    Use-after-free in the Graphics: Text component. This vulnerability was fixed in Firefox 154, Firefox ESR     115.39, Firefox ESR 140.14, and Firefox ESR 153.1. (CVE-2026-74940)

    Privilege escalation in the Graphics: CanvasWebGL component. This vulnerability was fixed in Firefox 154,     Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
    (CVE-2026-74941)

    Privilege escalation in the Remote Settings Client component. This vulnerability was fixed in Firefox 154,     Firefox ESR 115.39, Firefox ESR 140.14, and Firefox ESR 153.1. (CVE-2026-74942)

    Use-after-free in the Graphics: ImageLib component. This vulnerability was fixed in Firefox 154, Firefox     ESR 115.39, Firefox ESR 140.14, and Firefox ESR 153.1. (CVE-2026-74943)

    Use-after-free in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 154, Firefox ESR     140.14, and Firefox ESR 153.1. (CVE-2026-74944)

    Information disclosure in the Graphics: Text component. This vulnerability was fixed in Firefox 154,     Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and     Thunderbird 153.1. (CVE-2026-74945)

    Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component. This     vulnerability was fixed in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, and Firefox ESR 153.1.
    (CVE-2026-74946)

    Information disclosure in the Graphics component. This vulnerability was fixed in Firefox 154, Firefox ESR     115.39, Firefox ESR 140.14, and Firefox ESR 153.1. (CVE-2026-74948)

    Privilege escalation due to use-after-free in the Graphics: Canvas2D component. This vulnerability was     fixed in Firefox 154, Firefox ESR 140.14, and Firefox ESR 153.1. (CVE-2026-74949)

    Privilege escalation in the Downloads API component. This vulnerability was fixed in Firefox 154, Firefox     ESR 153.1, Thunderbird 154, and Thunderbird 153.1. (CVE-2026-74950)

    Privilege escalation in the Networking: Cookies component. This vulnerability was fixed in Firefox 154,     Firefox ESR 140.14, and Firefox ESR 153.1. (CVE-2026-74953)

    Mitigation bypass in the Safe Browsing component. This vulnerability was fixed in Firefox 154, Firefox ESR     140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1. (CVE-2026-74957)

    Mitigation bypass in the Storage: Cache API component. This vulnerability was fixed in Firefox 154,     Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
    (CVE-2026-74959)

    Site isolation issue in the WebExtensions component. This vulnerability was fixed in Firefox 154, Firefox     ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
    (CVE-2026-74960)

    Site isolation issue in the Networking: Cookies component. This vulnerability was fixed in Firefox 154,     Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
    (CVE-2026-74962)

    Same-origin policy bypass in the Networking: Cookies component. This vulnerability was fixed in Firefox     154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
    (CVE-2026-74963)

    Integer overflow in the Graphics component. This vulnerability was fixed in Firefox 154, Firefox ESR     140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1. (CVE-2026-74964)

    Privilege escalation in the Shell Integration component. This vulnerability was fixed in Firefox 154,     Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
    (CVE-2026-74965)

    Same-origin policy bypass in the Audio/Video: Playback component. This vulnerability was fixed in Firefox     154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
    (CVE-2026-74967)

    Site isolation issue in the Graphics: WebRender component. This vulnerability was fixed in Firefox 154,     Firefox ESR 153.1, Thunderbird 154, and Thunderbird 153.1. (CVE-2026-74968)

    Use-after-free in the Layout: Text and Fonts component. This vulnerability was fixed in Firefox 154,     Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and     Thunderbird 153.1. (CVE-2026-74969)

    Information disclosure in the DOM: UI Events & Focus Handling component. This vulnerability was fixed in     Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird     153.1. (CVE-2026-74971)

    Information disclosure in the DOM: Push Subscriptions component. This vulnerability was fixed in Firefox     154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
    (CVE-2026-74972)

    Race condition, use-after-free in the Graphics component. This vulnerability was fixed in Firefox 154,     Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and     Thunderbird 153.1. (CVE-2026-74973)

    Same-origin policy bypass in the Graphics: ImageLib component. This vulnerability was fixed in Firefox     154, Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and     Thunderbird 153.1. (CVE-2026-74974)

    JIT miscompilation in the JavaScript Engine: JIT component. This vulnerability was fixed in Firefox 154,     Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
    (CVE-2026-74976)

    Mitigation bypass in the Data Loss Prevention component. This vulnerability was fixed in Firefox 154,     Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
    (CVE-2026-74983)

    Internally found bugs present in Thunderbird ESR 140.13, Thunderbird ESR 153.0 and Thunderbird 153. Some     of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that     with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 154,     Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
    (CVE-2026-74987)

    Internally found bugs present in Thunderbird ESR 153.0 and Thunderbird 153. Some of these bugs showed     evidence of memory corruption or another security-relevant defect and we presume that with enough effort     some of these could have been exploited. This vulnerability was fixed in Firefox 154, Firefox ESR 153.1,     Thunderbird 154, and Thunderbird 153.1. (CVE-2026-74988)

    Internally found bugs present in Thunderbird ESR 140.13, Thunderbird ESR 153.0 and Thunderbird 153. Some     of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that     with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 154,     Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and     Thunderbird 153.1. (CVE-2026-74990)

    libexpat before 2.8.4 lacks handler call depth tracking with custom encoding callbacks. Thus, a use-after-     free can occur. NOTE: this is similar to CVE-2026-50219, CVE-2026-56131 and CVE-2026-56412.
    (CVE-2026-76957)

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 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.

It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2023-2026-2105 advisory.

    Expat through 2.8.3 contains a denial of service vulnerability caused by quadratic algorithmic complexity     in the storeAtts() function in xmlparse.c, where processing N specified attributes with non-normalized     values triggers an O(N^2) linear scan of elementType->defaultAtts to determine CDATA status. A remote     unauthenticated attacker can supply a single well-formed XML document of a few megabytes to an application     parsing untrusted XML to cause excessive CPU consumption, resulting in denial of service without requiring     authentication, external entity resolution, or non-default parser options. (CVE-2026-66046)

    libexpat before 2.8.3 has an out-of-bounds read and resultant infinite loop because low surrogates are     treated the same as high surrogates during Unicode processing in the *_toUtf16 functions. (CVE-2026-72522)

    Site isolation issue in the Graphics: CanvasWebGL component. This vulnerability was fixed in Firefox 154,     Firefox ESR 115.39, Firefox ESR 140.14, and Firefox ESR 153.1. (CVE-2026-74934)

    Privilege escalation in the DOM: Networking component. This vulnerability was fixed in Firefox 154,     Firefox ESR 115.39, Firefox ESR 140.14, and Firefox ESR 153.1. (CVE-2026-74935)

    Use-after-free in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox 154,     Firefox ESR 140.14, and Firefox ESR 153.1. (CVE-2026-74936)

    Mitigation bypass in the JavaScript: GC component. This vulnerability was fixed in Firefox 154, Firefox     ESR 153.1, Thunderbird 154, and Thunderbird 153.1. (CVE-2026-74938)

    Privilege escalation in the DOM: Navigation component. This vulnerability was fixed in Firefox 154,     Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and     Thunderbird 153.1. (CVE-2026-74939)

    Use-after-free in the Graphics: Text component. This vulnerability was fixed in Firefox 154, Firefox ESR     115.39, Firefox ESR 140.14, and Firefox ESR 153.1. (CVE-2026-74940)

    Privilege escalation in the Graphics: CanvasWebGL component. This vulnerability was fixed in Firefox 154,     Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
    (CVE-2026-74941)

    Privilege escalation in the Remote Settings Client component. This vulnerability was fixed in Firefox 154,     Firefox ESR 115.39, Firefox ESR 140.14, and Firefox ESR 153.1. (CVE-2026-74942)

    Use-after-free in the Graphics: ImageLib component. This vulnerability was fixed in Firefox 154, Firefox     ESR 115.39, Firefox ESR 140.14, and Firefox ESR 153.1. (CVE-2026-74943)

    Use-after-free in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 154, Firefox ESR     140.14, and Firefox ESR 153.1. (CVE-2026-74944)

    Information disclosure in the Graphics: Text component. This vulnerability was fixed in Firefox 154,     Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and     Thunderbird 153.1. (CVE-2026-74945)

    Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component. This     vulnerability was fixed in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, and Firefox ESR 153.1.
    (CVE-2026-74946)

    Information disclosure in the Graphics component. This vulnerability was fixed in Firefox 154, Firefox ESR     115.39, Firefox ESR 140.14, and Firefox ESR 153.1. (CVE-2026-74948)

    Privilege escalation due to use-after-free in the Graphics: Canvas2D component. This vulnerability was     fixed in Firefox 154, Firefox ESR 140.14, and Firefox ESR 153.1. (CVE-2026-74949)

    Privilege escalation in the Downloads API component. This vulnerability was fixed in Firefox 154, Firefox     ESR 153.1, Thunderbird 154, and Thunderbird 153.1. (CVE-2026-74950)

    Privilege escalation in the Networking: Cookies component. This vulnerability was fixed in Firefox 154,     Firefox ESR 140.14, and Firefox ESR 153.1. (CVE-2026-74953)

    Mitigation bypass in the Safe Browsing component. This vulnerability was fixed in Firefox 154, Firefox ESR     140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1. (CVE-2026-74957)

    Mitigation bypass in the Storage: Cache API component. This vulnerability was fixed in Firefox 154,     Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
    (CVE-2026-74959)

    Site isolation issue in the WebExtensions component. This vulnerability was fixed in Firefox 154, Firefox     ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
    (CVE-2026-74960)

    Site isolation issue in the Networking: Cookies component. This vulnerability was fixed in Firefox 154,     Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
    (CVE-2026-74962)

    Same-origin policy bypass in the Networking: Cookies component. This vulnerability was fixed in Firefox     154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
    (CVE-2026-74963)

    Integer overflow in the Graphics component. This vulnerability was fixed in Firefox 154, Firefox ESR     140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1. (CVE-2026-74964)

    Privilege escalation in the Shell Integration component. This vulnerability was fixed in Firefox 154,     Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
    (CVE-2026-74965)

    Same-origin policy bypass in the Audio/Video: Playback component. This vulnerability was fixed in Firefox     154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
    (CVE-2026-74967)

    Site isolation issue in the Graphics: WebRender component. This vulnerability was fixed in Firefox 154,     Firefox ESR 153.1, Thunderbird 154, and Thunderbird 153.1. (CVE-2026-74968)

    Use-after-free in the Layout: Text and Fonts component. This vulnerability was fixed in Firefox 154,     Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and     Thunderbird 153.1. (CVE-2026-74969)

    Information disclosure in the DOM: UI Events & Focus Handling component. This vulnerability was fixed in     Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird     153.1. (CVE-2026-74971)

    Information disclosure in the DOM: Push Subscriptions component. This vulnerability was fixed in Firefox     154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
    (CVE-2026-74972)

    Race condition, use-after-free in the Graphics component. This vulnerability was fixed in Firefox 154,     Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and     Thunderbird 153.1. (CVE-2026-74973)

    Same-origin policy bypass in the Graphics: ImageLib component. This vulnerability was fixed in Firefox     154, Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and     Thunderbird 153.1. (CVE-2026-74974)

    JIT miscompilation in the JavaScript Engine: JIT component. This vulnerability was fixed in Firefox 154,     Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
    (CVE-2026-74976)

    Mitigation bypass in the Data Loss Prevention component. This vulnerability was fixed in Firefox 154,     Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
    (CVE-2026-74983)

    Internally found bugs present in Thunderbird ESR 140.13, Thunderbird ESR 153.0 and Thunderbird 153. Some     of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that     with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 154,     Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
    (CVE-2026-74987)

    Internally found bugs present in Thunderbird ESR 153.0 and Thunderbird 153. Some of these bugs showed     evidence of memory corruption or another security-relevant defect and we presume that with enough effort     some of these could have been exploited. This vulnerability was fixed in Firefox 154, Firefox ESR 153.1,     Thunderbird 154, and Thunderbird 153.1. (CVE-2026-74988)

    Internally found bugs present in Thunderbird ESR 140.13, Thunderbird ESR 153.0 and Thunderbird 153. Some     of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that     with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 154,     Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and     Thunderbird 153.1. (CVE-2026-74990)

    libexpat before 2.8.4 lacks handler call depth tracking with custom encoding callbacks. Thus, a use-after-     free can occur. NOTE: this is similar to CVE-2026-50219, CVE-2026-56131 and CVE-2026-56412.
    (CVE-2026-76957)

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 140.14.0-1. It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2-2026-3880 advisory.

    Expat through 2.8.3 contains a denial of service vulnerability caused by quadratic algorithmic complexity     in the storeAtts() function in xmlparse.c, where processing N specified attributes with non-normalized     values triggers an O(N^2) linear scan of elementType->defaultAtts to determine CDATA status. A remote     unauthenticated attacker can supply a single well-formed XML document of a few megabytes to an application     parsing untrusted XML to cause excessive CPU consumption, resulting in denial of service without requiring     authentication, external entity resolution, or non-default parser options. (CVE-2026-66046)

    libexpat before 2.8.3 has an out-of-bounds read and resultant infinite loop because low surrogates are     treated the same as high surrogates during Unicode processing in the *_toUtf16 functions. (CVE-2026-72522)

    Site isolation issue in the Graphics: CanvasWebGL component. This vulnerability was fixed in Firefox 154,     Firefox ESR 115.39, Firefox ESR 140.14, and Firefox ESR 153.1. (CVE-2026-74934)

    Privilege escalation in the DOM: Networking component. This vulnerability was fixed in Firefox 154,     Firefox ESR 115.39, Firefox ESR 140.14, and Firefox ESR 153.1. (CVE-2026-74935)

    Use-after-free in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox 154,     Firefox ESR 140.14, and Firefox ESR 153.1. (CVE-2026-74936)

    Mitigation bypass in the JavaScript: GC component. This vulnerability was fixed in Firefox 154, Firefox     ESR 153.1, Thunderbird 154, and Thunderbird 153.1. (CVE-2026-74938)

    Privilege escalation in the DOM: Navigation component. This vulnerability was fixed in Firefox 154,     Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and     Thunderbird 153.1. (CVE-2026-74939)

    Use-after-free in the Graphics: Text component. This vulnerability was fixed in Firefox 154, Firefox ESR     115.39, Firefox ESR 140.14, and Firefox ESR 153.1. (CVE-2026-74940)

    Privilege escalation in the Graphics: CanvasWebGL component. This vulnerability was fixed in Firefox 154,     Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
    (CVE-2026-74941)

    Privilege escalation in the Remote Settings Client component. This vulnerability was fixed in Firefox 154,     Firefox ESR 115.39, Firefox ESR 140.14, and Firefox ESR 153.1. (CVE-2026-74942)

    Use-after-free in the Graphics: ImageLib component. This vulnerability was fixed in Firefox 154, Firefox     ESR 115.39, Firefox ESR 140.14, and Firefox ESR 153.1. (CVE-2026-74943)

    Use-after-free in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 154, Firefox ESR     140.14, and Firefox ESR 153.1. (CVE-2026-74944)

    Information disclosure in the Graphics: Text component. This vulnerability was fixed in Firefox 154,     Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and     Thunderbird 153.1. (CVE-2026-74945)

    Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component. This     vulnerability was fixed in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, and Firefox ESR 153.1.
    (CVE-2026-74946)

    Information disclosure in the Graphics component. This vulnerability was fixed in Firefox 154, Firefox ESR     115.39, Firefox ESR 140.14, and Firefox ESR 153.1. (CVE-2026-74948)

    Privilege escalation due to use-after-free in the Graphics: Canvas2D component. This vulnerability was     fixed in Firefox 154, Firefox ESR 140.14, and Firefox ESR 153.1. (CVE-2026-74949)

    Privilege escalation in the Downloads API component. This vulnerability was fixed in Firefox 154, Firefox     ESR 153.1, Thunderbird 154, and Thunderbird 153.1. (CVE-2026-74950)

    Privilege escalation in the Networking: Cookies component. This vulnerability was fixed in Firefox 154,     Firefox ESR 140.14, and Firefox ESR 153.1. (CVE-2026-74953)

    Mitigation bypass in the Safe Browsing component. This vulnerability was fixed in Firefox 154, Firefox ESR     140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1. (CVE-2026-74957)

    Mitigation bypass in the Storage: Cache API component. This vulnerability was fixed in Firefox 154,     Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
    (CVE-2026-74959)

    Site isolation issue in the WebExtensions component. This vulnerability was fixed in Firefox 154, Firefox     ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
    (CVE-2026-74960)

    Site isolation issue in the Networking: Cookies component. This vulnerability was fixed in Firefox 154,     Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
    (CVE-2026-74962)

    Same-origin policy bypass in the Networking: Cookies component. This vulnerability was fixed in Firefox     154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
    (CVE-2026-74963)

    Integer overflow in the Graphics component. This vulnerability was fixed in Firefox 154, Firefox ESR     140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1. (CVE-2026-74964)

    Privilege escalation in the Shell Integration component. This vulnerability was fixed in Firefox 154,     Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
    (CVE-2026-74965)

    Same-origin policy bypass in the Audio/Video: Playback component. This vulnerability was fixed in Firefox     154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
    (CVE-2026-74967)

    Site isolation issue in the Graphics: WebRender component. This vulnerability was fixed in Firefox 154,     Firefox ESR 153.1, Thunderbird 154, and Thunderbird 153.1. (CVE-2026-74968)

    Use-after-free in the Layout: Text and Fonts component. This vulnerability was fixed in Firefox 154,     Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and     Thunderbird 153.1. (CVE-2026-74969)

    Information disclosure in the DOM: UI Events & Focus Handling component. This vulnerability was fixed in     Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird     153.1. (CVE-2026-74971)

    Information disclosure in the DOM: Push Subscriptions component. This vulnerability was fixed in Firefox     154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
    (CVE-2026-74972)

    Race condition, use-after-free in the Graphics component. This vulnerability was fixed in Firefox 154,     Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and     Thunderbird 153.1. (CVE-2026-74973)

    Same-origin policy bypass in the Graphics: ImageLib component. This vulnerability was fixed in Firefox     154, Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and     Thunderbird 153.1. (CVE-2026-74974)

    JIT miscompilation in the JavaScript Engine: JIT component. This vulnerability was fixed in Firefox 154,     Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
    (CVE-2026-74976)

    Mitigation bypass in the Data Loss Prevention component. This vulnerability was fixed in Firefox 154,     Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
    (CVE-2026-74983)

    Internally found bugs present in Thunderbird ESR 140.13, Thunderbird ESR 153.0 and Thunderbird 153. Some     of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that     with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 154,     Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
    (CVE-2026-74987)

    Internally found bugs present in Thunderbird ESR 153.0 and Thunderbird 153. Some of these bugs showed     evidence of memory corruption or another security-relevant defect and we presume that with enough effort     some of these could have been exploited. This vulnerability was fixed in Firefox 154, Firefox ESR 153.1,     Thunderbird 154, and Thunderbird 153.1. (CVE-2026-74988)

    Internally found bugs present in Thunderbird ESR 140.13, Thunderbird ESR 153.0 and Thunderbird 153. Some     of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that     with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 154,     Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and     Thunderbird 153.1. (CVE-2026-74990)

    libexpat before 2.8.4 lacks handler call depth tracking with custom encoding callbacks. Thus, a use-after-     free can occur. NOTE: this is similar to CVE-2026-50219, CVE-2026-56131 and CVE-2026-56412.
    (CVE-2026-76957)

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

  - libexpat before 2.8.4 lacks handler call depth tracking with custom encoding callbacks. Thus, a use-after-     free can occur. NOTE: this is similar to CVE-2026-50219, CVE-2026-56131 and CVE-2026-56412.
    (CVE-2026-76957)

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

ID	Name	Product	Family	Published	Updated	Severity
447379	Alpine: libexpat, multiple expat packages: security update to 2.8.4-r0	Tenable Self-Hosted Container Security	Alpine Linux Local Security Checks	9/1/2026	9/9/2026	high
447379	Alpine: libexpat, multiple expat packages: security update to 2.8.4-r0	Tenable Cloud Security	Alpine Linux Local Security Checks	9/1/2026	9/9/2026	high
341890	Amazon Linux 2 : firefox, --advisory ALAS2FIREFOX-2026-064 (ALASFIREFOX-2026-064)	Nessus	Amazon Linux Local Security Checks	8/31/2026	9/3/2026	high
341830	Debian dla-4765 : expat - security update	Nessus	Debian Local Security Checks	8/31/2026	9/10/2026	high
341868	Amazon Linux 2023 : firefox (ALAS2023-2026-2105)	Nessus	Amazon Linux Local Security Checks	8/31/2026	9/3/2026	high
341839	Amazon Linux 2 : thunderbird, --advisory ALAS2-2026-3880 (ALAS-2026-3880)	Nessus	Amazon Linux Local Security Checks	8/31/2026	9/3/2026	high
338296	Linux Distros Unpatched Vulnerability : CVE-2026-76957	Nessus	Misc.	8/20/2026	9/10/2026	high

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