libexpat versions 2.7.2 through 2.8.5 contain an integer overflow vulnerability in expat_realloc() function on 32-bit platforms when computing allocation sizes. Attackers supplying malicious XML to applications parsing with vulnerable libexpat can cause heap buffer overflow, memory corruption, or denial of service.

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

  - libexpat before commit 13c5f63 contains a heap buffer over-read vulnerability in xmlparse.c.
    XML_ParseBuffer advances the parse buffer end with parser->m_bufferEnd += len using a caller-supplied
    length that is not validated against the allocated buffer size, so repeated XML_ParseBuffer calls move
    m_bufferEnd past the end of the heap allocation and subsequent parsing reads out of bounds. Reaching this
    path requires a parse buffer to already be present; otherwise XML_ParseBuffer returns XML_ERROR_NO_BUFFER.
    A buffer is present after a prior call to XML_GetBuffer, either directly (the common case) or indirectly
    through a prior XML_Parse call that allocates the buffer internally. The over-read discloses adjacent heap
    memory to the calling application, recovering heap pointers, libc function pointers, and code pointers
    sufficient to defeat ASLR and build further exploitation primitives. (CVE-2026-77214)

  - libexpat versions 2.7.2 through 2.8.5 contain an integer overflow vulnerability in expat_realloc()
    function on 32-bit platforms when computing allocation sizes. Attackers supplying malicious XML to
    applications parsing with vulnerable libexpat can cause heap buffer overflow, memory corruption, or denial
    of service. (CVE-2026-102633)

The remote Debian 13 host has packages installed that are affected by multiple vulnerabilities as referenced in the dsa-6566 advisory.

    - -------------------------------------------------------------------------     Debian Security Advisory DSA-6566-1                   security@debian.org     https://www.debian.org/security/                     Salvatore Bonaccorso     October 16, 2026                      https://www.debian.org/security/faq
    - -------------------------------------------------------------------------

    Package        : expat     CVE ID         : CVE-2026-66046 CVE-2026-76956 CVE-2026-76957 CVE-2026-77214                      CVE-2026-93990 CVE-2026-102633     Debian Bug     : 1144925 1144926 1144927 1148665 1149507 1150320

    Several vulnerabilities have been discovered in Expat, an XML parsing C     library, which could result in denial of service or potentially the     execution of arbitrary code, if a malformed XML file is processed.

    For the stable distribution (trixie), these problems have been fixed in     version 2.9.0-1~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.

The version of expat installed on the remote host is prior to 2.9.0. It is, therefore, affected by multiple vulnerabilities as referenced in the SSA:2026-286-01 advisory.

    New expat packages are available for Slackware 15.0 and -current to fix security issues.

Tenable has extracted the preceding description block directly from the 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 SUSE Linux SLES12 / SLES_SAP12 host has packages installed that are affected by multiple vulnerabilities as referenced in the SUSE-SU-2026:4615-1 advisory.

    - CVE-2025-59375: denial of service (resource consumption) caused by processing malformed small documents     (bsc#1249584).
    - CVE-2026-24515: NULL dereference (CWE-476) due to function XML_ExternalEntityParserCreate() failing to     copy the       encoding handler data passed to XML_SetUnknownEncodingHandler() from the parent to the subparser     (bsc#1257144).
    - CVE-2026-25210: lack of buffer size check can lead to an integer overflow (bsc#1257496).
    - CVE-2026-32776: NULL pointer dereference when processing empty external parameter entities inside an     entity       declaration value (bsc#1259726).
    - CVE-2026-32777: denial of service due to infinite loop in DTD content parsing (bsc#1259711).
    - CVE-2026-32778: NULL pointer dereference in `setContext` on retry after an out-of-memory condition       (bsc#1259729).
    - CVE-2026-41080: crafted XML document can cause a denial of service (bsc#1262263).
    - CVE-2026-45186: denial of service via moderately sized crafted XML input (bsc#1264713).
    - CVE-2026-50219: lack of handler call depth tracking for calls to XML_* functions from within handlers in     cases of a       policy violation (bsc#1267631).
    - CVE-2026-56131: lack of handler call depth tracking for calls to XML_ResumeParser from within       handlers in cases of a policy violation (bsc#1268572).
    - CVE-2026-56132: heap-based buffer overflow in doProlog in xmlparse.c (bsc#1268573).
    - 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 integer overflow vulnerabilities (bsc#1275115).
    - CVE-2026-66046: denial of service vulnerability caused by quadratic algorithmic complexity in the     storeAtts()       function (bsc#1275732).
    - CVE-2026-72522: out-of-bounds read and resultant infinite loop due to low surrogates being treated the     same       as high surrogates during Unicode processing (bsc#1275594).
    - CVE-2026-76641: out-of-bounds read vulnerability that allows attackers to trigger       memory corruption (bsc#1275915).
    - CVE-2026-76956: denial of service via hash flooding attacks (bsc#1275860).
    - CVE-2026-76957: lack of handler call depth tracking with custom encoding callbacks. Thus, a use-       after-free can occur (bsc#1275859).
    - CVE-2026-77214: out-of-bounds read due to insufficient checks in `XML_ParseBuffer()` (bsc#1284334).
    - CVE-2026-93990: fails to validate low surrogates following high surrogates in UTF-16 input     (bsc#1282347).
    - CVE-2026-102633: Denial of Service via integer overflow in expat_realloc (bsc#1283493).

    Update to 2.8.5 (jsc#PED-16154):

     * Bug fixes:
     * Fix an OOM-related memory leak on a failed overflow check
     * Fix memory alignment for architectures with 128bit pointers
     * Mark XML_SetHashSalt deprecated
     * CMake: only add /source-charset:utf-8 when /utf-8 is not present
     * lib: resolve undefined behavior from overshifting a signed int
     * lib: support read-only hash table lookup with non-zero-terminated      keys
     * lib: use a C99 bool for ENTITY.open
     * version info bumped from 13:3:12 to 13:4:12
     * fix support for 2+ GiB documents (regression from 2.8.2)
     * reject empty version in the XML declaration
     * fix printf format for AIX
     * CMake|AIX: enable EXPAT_DEV_URANDOM by default
     * version info bumped from 13:2:12 to 13:3:12
     * Existing API function XML_SetHashSalt is now deprecated
     * because of its limitations, and its use should be
     * considered a vulnerability. Please either use the new API
     * function XML_SetHashSalt16Bytes (with known-high-quality
     * entropy input only!) instead, or leave the derivation of
     * a 16-bytes hash salt from high quality entropy to Expat's
     * internal machinery (by *not* calling either of the two
     * XML_SetHashSalt* functions).
     * xmlwf: Fix a memory leak
     * WASI: Fix format specifiers for 32bit WASI SDK
     * Fix alignment of internal allocations for some non-amd64      architectures (e.g. sparc32); fixes up on the fix to      CVE-2025-59375 (of Expat 2.7.2)
     * Fix a class of false positives where input should have been      rejected with error XML_ERROR_ASYNC_ENTITY; regression from      CVE-2024-8176 (of Expat 2.7.0)
     * Prove and regression-proof absence of integer overflow      from function expat_realloc
     * Remove 'harmless' cast that truncated a size_t to unsigned
     * xmlwf: Resolve use of functions XML_GetErrorLineNumber      and XML_GetErrorColumnNumber
     * CVE-2025-59375 -- Disallow use of disproportional amounts of      dynamic memory from within an Expat parser
     * xmlwf: Fix (internal) help generator
     * xmlwf: Mention supported environment variables in

Tenable has extracted the preceding description block directly from the SUSE 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 SUSE Linux SLED15 / SLED_SAP15 / SLES15 / SLES_SAP15 host has packages installed that are affected by multiple vulnerabilities as referenced in the SUSE-SU-2026:4619-1 advisory.

    - CVE-2025-59375: denial of service (resource consumption) caused by processing malformed small documents     (bsc#1249584).
    - CVE-2026-24515: NULL dereference (CWE-476) due to function XML_ExternalEntityParserCreate() failing to     copy the       encoding handler data passed to XML_SetUnknownEncodingHandler() from the parent to the subparser     (bsc#1257144).
    - CVE-2026-25210: lack of buffer size check can lead to an integer overflow (bsc#1257496).
    - CVE-2026-32776: NULL pointer dereference when processing empty external parameter entities inside an     entity       declaration value (bsc#1259726).
    - CVE-2026-32777: denial of service due to infinite loop in DTD content parsing (bsc#1259711).
    - CVE-2026-32778: NULL pointer dereference in `setContext` on retry after an out-of-memory condition       (bsc#1259729).
    - CVE-2026-41080: crafted XML document can cause a denial of service (bsc#1262263).
    - CVE-2026-45186: denial of service via moderately sized crafted XML input (bsc#1264713).
    - CVE-2026-50219: lack of handler call depth tracking for calls to XML_* functions from within handlers in     cases of a       policy violation (bsc#1267631).
    - CVE-2026-56131: lack of handler call depth tracking for calls to XML_ResumeParser from within       handlers in cases of a policy violation (bsc#1268572).
    - CVE-2026-56132: heap-based buffer overflow in doProlog in xmlparse.c (bsc#1268573).
    - 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 integer overflow vulnerabilities (bsc#1275115).
    - CVE-2026-66046: denial of service vulnerability caused by quadratic algorithmic complexity in the     storeAtts()       function (bsc#1275732).
    - CVE-2026-72522: out-of-bounds read and resultant infinite loop due to low surrogates being treated the     same       as high surrogates during Unicode processing (bsc#1275594).
    - CVE-2026-76641: out-of-bounds read vulnerability that allows attackers to trigger       memory corruption (bsc#1275915).
    - CVE-2026-76956: denial of service via hash flooding attacks (bsc#1275860).
    - CVE-2026-76957: lack of handler call depth tracking with custom encoding callbacks. Thus, a use-       after-free can occur (bsc#1275859).
    - CVE-2026-77214: out-of-bounds read due to insufficient checks in `XML_ParseBuffer()` (bsc#1284334).
    - CVE-2026-93990: fails to validate low surrogates following high surrogates in UTF-16 input     (bsc#1282347).
    - CVE-2026-102633: Denial of Service via integer overflow in expat_realloc (bsc#1283493).

    Update to 2.8.5 (jsc#PED-16154):

     * Bug fixes:
     * Fix an OOM-related memory leak on a failed overflow check
     * Fix memory alignment for architectures with 128bit pointers
     * Mark XML_SetHashSalt deprecated
     * CMake: only add /source-charset:utf-8 when /utf-8 is not present
     * lib: resolve undefined behavior from overshifting a signed int
     * lib: support read-only hash table lookup with non-zero-terminated      keys
     * lib: use a C99 bool for ENTITY.open
     * version info bumped from 13:3:12 to 13:4:12
     * fix support for 2+ GiB documents (regression from 2.8.2)
     * reject empty version in the XML declaration
     * fix printf format for AIX
     * CMake|AIX: enable EXPAT_DEV_URANDOM by default
     * version info bumped from 13:2:12 to 13:3:12
     * Existing API function XML_SetHashSalt is now deprecated
     * because of its limitations, and its use should be
     * considered a vulnerability. Please either use the new API
     * function XML_SetHashSalt16Bytes (with known-high-quality
     * entropy input only!) instead, or leave the derivation of
     * a 16-bytes hash salt from high quality entropy to Expat's
     * internal machinery (by *not* calling either of the two
     * XML_SetHashSalt* functions).
     * xmlwf: Fix a memory leak
     * WASI: Fix format specifiers for 32bit WASI SDK
     * Fix a class of false positives where input should have been        rejected with error XML_ERROR_ASYNC_ENTITY; regression from        earlier security fix (of Expat 2.7.0)
     * Prove and regression-proof absence of integer overflow      from function expat_realloc
     * Remove 'harmless' cast that truncated a size_t to unsigned
     * xmlwf: Resolve use of functions XML_GetErrorLineNumber        and XML_GetErrorColumnNumber
     * CVE-2025-59375 -- Disallow use of disproportional amounts of        dynamic memory from within an Expat parser
     * xmlwf: Fix (internal) help generator
     * xmlwf: Mention supported environment variables in

Tenable has extracted the preceding description block directly from the SUSE 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 SUSE Linux SLES15 / SLES_SAP15 host has packages installed that are affected by multiple vulnerabilities as referenced in the SUSE-SU-2026:4623-1 advisory.

    - CVE-2025-59375: denial of service (resource consumption) caused by processing malformed small documents     (bsc#1249584).
    - CVE-2026-24515: NULL dereference (CWE-476) due to function XML_ExternalEntityParserCreate() failing to     copy the       encoding handler data passed to XML_SetUnknownEncodingHandler() from the parent to the subparser     (bsc#1257144).
    - CVE-2026-25210: lack of buffer size check can lead to an integer overflow (bsc#1257496).
    - CVE-2026-32776: NULL pointer dereference when processing empty external parameter entities inside an     entity       declaration value (bsc#1259726).
    - CVE-2026-32777: denial of service due to infinite loop in DTD content parsing (bsc#1259711).
    - CVE-2026-32778: NULL pointer dereference in `setContext` on retry after an out-of-memory condition       (bsc#1259729).
    - CVE-2026-41080: crafted XML document can cause a denial of service (bsc#1262263).
    - CVE-2026-45186: denial of service via moderately sized crafted XML input (bsc#1264713).
    - CVE-2026-50219: lack of handler call depth tracking for calls to XML_* functions from within handlers in     cases of a       policy violation (bsc#1267631).
    - CVE-2026-56131: lack of handler call depth tracking for calls to XML_ResumeParser from within       handlers in cases of a policy violation (bsc#1268572).
    - CVE-2026-56132: heap-based buffer overflow in doProlog in xmlparse.c (bsc#1268573).
    - 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 integer overflow vulnerabilities (bsc#1275115).
    - CVE-2026-66046: denial of service vulnerability caused by quadratic algorithmic complexity in the     storeAtts()       function (bsc#1275732).
    - CVE-2026-72522: out-of-bounds read and resultant infinite loop due to low surrogates being treated the     same       as high surrogates during Unicode processing (bsc#1275594).
    - CVE-2026-76641: out-of-bounds read vulnerability that allows attackers to trigger       memory corruption (bsc#1275915).
    - CVE-2026-76956: denial of service via hash flooding attacks (bsc#1275860).
    - CVE-2026-76957: lack of handler call depth tracking with custom encoding callbacks. Thus, a use-       after-free can occur (bsc#1275859).
    - CVE-2026-77214: out-of-bounds read due to insufficient checks in `XML_ParseBuffer()` (bsc#1284334).
    - CVE-2026-93990: fails to validate low surrogates following high surrogates in UTF-16 input     (bsc#1282347).
    - CVE-2026-102633: Denial of Service via integer overflow in expat_realloc (bsc#1283493).

    Update to 2.8.5 (jsc#PED-16154):

     * Bug fixes:
     * Fix an OOM-related memory leak on a failed overflow check
     * Fix memory alignment for architectures with 128bit pointers
     * Mark XML_SetHashSalt deprecated
     * CMake: only add /source-charset:utf-8 when /utf-8 is not present
     * lib: resolve undefined behavior from overshifting a signed int
     * lib: support read-only hash table lookup with non-zero-terminated      keys
     * lib: use a C99 bool for ENTITY.open
     * version info bumped from 13:3:12 to 13:4:12
     * fix support for 2+ GiB documents (regression from 2.8.2)
     * reject empty version in the XML declaration
     * fix printf format for AIX
     * CMake|AIX: enable EXPAT_DEV_URANDOM by default
     * version info bumped from 13:2:12 to 13:3:12
     * Existing API function XML_SetHashSalt is now deprecated
     * because of its limitations, and its use should be
     * considered a vulnerability. Please either use the new API
     * function XML_SetHashSalt16Bytes (with known-high-quality
     * entropy input only!) instead, or leave the derivation of
     * a 16-bytes hash salt from high quality entropy to Expat's
     * internal machinery (by *not* calling either of the two
     * XML_SetHashSalt* functions).
     * xmlwf: Fix a memory leak
     * WASI: Fix format specifiers for 32bit WASI SDK
     * Fix alignment of internal allocations for some non-amd64      architectures (e.g. sparc32); fixes up on the fix to      CVE-2025-59375 (of Expat 2.7.2)
     * Fix a class of false positives where input should have been      rejected with error XML_ERROR_ASYNC_ENTITY; regression from      CVE-2024-8176 (of Expat 2.7.0)
     * Prove and regression-proof absence of integer overflow      from function expat_realloc
     * Remove 'harmless' cast that truncated a size_t to unsigned
     * xmlwf: Resolve use of functions XML_GetErrorLineNumber      and XML_GetErrorColumnNumber
     * CVE-2025-59375 -- Disallow use of disproportional amounts of      dynamic memory from within an Expat parser
     * xmlwf: Fix (internal) help generator
     * xmlwf: Mention supported environment variables in

Tenable has extracted the preceding description block directly from the SUSE 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 Rocky Linux 9.6 host has packages installed that are affected by a vulnerability as referenced in the TuxCare ALMALINUX9.6:CLSA-2026:1791791753 advisory.

  - libexpat versions 2.7.2 through 2.8.5 contain an integer overflow vulnerability in expat_realloc()     function on 32-bit platforms when computing allocation sizes. Attackers supplying malicious XML to     applications parsing with vulnerable libexpat can cause heap buffer overflow, memory corruption, or denial     of service. (CVE-2026-102633)

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

The AlmaLinux 9.6 host has packages installed that are affected by a vulnerability as referenced in the TuxCare ALMALINUX9.6:CLSA-2026:1791791753 advisory.

  - libexpat versions 2.7.2 through 2.8.5 contain an integer overflow vulnerability in expat_realloc()     function on 32-bit platforms when computing allocation sizes. Attackers supplying malicious XML to     applications parsing with vulnerable libexpat can cause heap buffer overflow, memory corruption, or denial     of service. (CVE-2026-102633)

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

The AlmaLinux 9.2 host has packages installed that are affected by a vulnerability as referenced in the TuxCare ALMALINUX9.2:CLSA-2026:1791196479 advisory.

  - libexpat versions 2.7.2 through 2.8.5 contain an integer overflow vulnerability in expat_realloc()     function on 32-bit platforms when computing allocation sizes. Attackers supplying malicious XML to     applications parsing with vulnerable libexpat can cause heap buffer overflow, memory corruption, or denial     of service. (CVE-2026-102633)

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

There are packages installed that are affected by a vulnerability referenced in the following CVE:

  - libexpat versions 2.7.2 through 2.8.5 contain an integer overflow vulnerability in expat_realloc()
    function on 32-bit platforms when computing allocation sizes. Attackers supplying malicious XML to
    applications parsing with vulnerable libexpat can cause heap buffer overflow, memory corruption, or denial
    of service. (CVE-2026-102633)

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

  - libexpat versions 2.7.2 through 2.8.5 contain an integer overflow vulnerability in expat_realloc()     function on 32-bit platforms when computing allocation sizes. Attackers supplying malicious XML to     applications parsing with vulnerable libexpat can cause heap buffer overflow, memory corruption, or denial     of service. (CVE-2026-102633)

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

ID	Name	Product	Family	Type	Severity
476120	Alpine: expat: security update to 2.9.0-r0	Tenable Cloud Security	Alpine Linux Local Security Checks	Local	high
476120	Alpine: expat: security update to 2.9.0-r0	Tenable Self-Hosted Container Security	Alpine Linux Local Security Checks	Local	high
366409	Debian dsa-6566 : expat - security update	Nessus	Debian Local Security Checks	Local	high
365529	Slackware Linux 15.0 / current expat Multiple Vulnerabilities (SSA:2026-286-01)	Nessus	Slackware Local Security Checks	Local	high
365325	SUSE SLES12 Security Update : expat (SUSE-SU-2026:4615-1)	Nessus	SuSE Local Security Checks	Local	high
365321	SUSE SLED15 / SLES15 Security Update : expat (SUSE-SU-2026:4619-1)	Nessus	SuSE Local Security Checks	Local	high
365317	SUSE SLES15 Security Update : expat (SUSE-SU-2026:4623-1)	Nessus	SuSE Local Security Checks	Local	high
365293	Amazon Linux 2 : firefox (ALASFIREFOX-2026-066)	Nessus	Amazon Linux Local Security Checks	Local	high
365225	Amazon Linux 2023 : firefox (ALAS2023-2026-3214)	Nessus	Amazon Linux Local Security Checks	Local	high
364676	Rocky Linux 9.6 [TuxCare] Security Update: expat / expat-devel / expat-static (ALMALINUX9.6:CLSA-2026:1791791753)	Nessus	Rocky Linux Local Security Checks	Local	high
364674	AlmaLinux 9.6 [TuxCare] Security Update: expat / expat-devel / expat-static (ALMALINUX9.6:CLSA-2026:1791791753)	Nessus	Alma Linux Local Security Checks	Local	high
362981	AlmaLinux 9.2 [TuxCare] Security Update: expat / expat-devel / expat-static (ALMALINUX9.2:CLSA-2026:1791196479)	Nessus	Alma Linux Local Security Checks	Local	high
461186	Echo: expat: security update to 2.9.0-1	Tenable Cloud Security	Echo Local Security Checks	Local	high
461186	Echo: expat: security update to 2.9.0-1	Tenable Self-Hosted Container Security	Echo Local Security Checks	Local	high
351184	Linux Distros Unpatched Vulnerability : CVE-2026-102633	Nessus	Misc.	Local	high

Detections

Analytics

CVE-2026-102633

high

Tenable Plugins

high

high

high

high

high

high

high

high

high

high

high

high

high

high

high