In libexpat before 2.7.4, the doContent function does not properly determine the buffer size bufSize because there is no integer overflow check for tag buffer reallocation.

The version of firefox installed on the remote host is prior to 140.7.0-1. It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2FIREFOX-2026-051 advisory.

    HarfBuzz is a text shaping engine. Prior to version 12.3.0, a null pointer dereference vulnerability     exists in the SubtableUnicodesCache::create function located in src/hb-ot-cmap-table.hh. The function     fails to check if hb_malloc returns NULL before using placement new to construct an object at the returned     pointer address. When hb_malloc fails to allocate memory (which can occur in low-memory conditions or when     using custom allocators that simulate allocation failures), it returns NULL. The code then attempts to     call the constructor on this null pointer using placement new syntax, resulting in undefined behavior and     a Segmentation Fault. This issue has been patched in version 12.3.0. (CVE-2026-22693)

    LIBPNG is a reference library for use in applications that read, create, and manipulate PNG (Portable     Network Graphics) raster image files. From 1.6.51 to 1.6.53, there is a heap buffer over-read in the     libpng simplified API function png_image_finish_read when processing interlaced 16-bit PNGs with 8-bit     output format and non-minimal row stride. This is a regression introduced by the fix for CVE-2025-65018.
    This vulnerability is fixed in 1.6.54. (CVE-2026-22695)

    LIBPNG is a reference library for use in applications that read, create, and manipulate PNG (Portable     Network Graphics) raster image files. From 1.6.26 to 1.6.53, there is an integer truncation in the libpng     simplified write API functions png_write_image_16bit and png_write_image_8bit causes heap buffer over-read     when the caller provides a negative row stride (for bottom-up image layouts) or a stride exceeding 65535     bytes. The bug was introduced in libpng 1.6.26 (October 2016) by casts added to silence compiler warnings     on 16-bit systems. This vulnerability is fixed in 1.6.54. (CVE-2026-22801)

    In libexpat before 2.7.4, the doContent function does not properly determine the buffer size bufSize     because there is no integer overflow check for tag buffer reallocation. (CVE-2026-25210)

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.

It is, therefore, affected by a vulnerability as referenced in the ALAS2023-2026-1424 advisory.

    In libexpat before 2.7.4, the doContent function does not properly determine the buffer size bufSize     because there is no integer overflow check for tag buffer reallocation. (CVE-2026-25210)

Tenable has extracted the preceding description block directly from the tested product 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 version of thunderbird installed on the remote host is prior to 140.7.1-1. It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2-2026-3171 advisory.

    HarfBuzz is a text shaping engine. Prior to version 12.3.0, a null pointer dereference vulnerability     exists in the SubtableUnicodesCache::create function located in src/hb-ot-cmap-table.hh. The function     fails to check if hb_malloc returns NULL before using placement new to construct an object at the returned     pointer address. When hb_malloc fails to allocate memory (which can occur in low-memory conditions or when     using custom allocators that simulate allocation failures), it returns NULL. The code then attempts to     call the constructor on this null pointer using placement new syntax, resulting in undefined behavior and     a Segmentation Fault. This issue has been patched in version 12.3.0. (CVE-2026-22693)

    LIBPNG is a reference library for use in applications that read, create, and manipulate PNG (Portable     Network Graphics) raster image files. From 1.6.51 to 1.6.53, there is a heap buffer over-read in the     libpng simplified API function png_image_finish_read when processing interlaced 16-bit PNGs with 8-bit     output format and non-minimal row stride. This is a regression introduced by the fix for CVE-2025-65018.
    This vulnerability is fixed in 1.6.54. (CVE-2026-22695)

    LIBPNG is a reference library for use in applications that read, create, and manipulate PNG (Portable     Network Graphics) raster image files. From 1.6.26 to 1.6.53, there is an integer truncation in the libpng     simplified write API functions png_write_image_16bit and png_write_image_8bit causes heap buffer over-read     when the caller provides a negative row stride (for bottom-up image layouts) or a stride exceeding 65535     bytes. The bug was introduced in libpng 1.6.26 (October 2016) by casts added to silence compiler warnings     on 16-bit systems. This vulnerability is fixed in 1.6.54. (CVE-2026-22801)

    In libexpat before 2.7.4, the doContent function does not properly determine the buffer size bufSize     because there is no integer overflow check for tag buffer reallocation. (CVE-2026-25210)

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 expat installed on the remote host is prior to 2.1.0-15. It is, therefore, affected by a vulnerability as referenced in the ALAS2-2026-3170 advisory.

    In libexpat before 2.7.4, the doContent function does not properly determine the buffer size bufSize     because there is no integer overflow check for tag buffer reallocation. (CVE-2026-25210)

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

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

It is, therefore, affected by a vulnerability as referenced in the ALAS2023-2026-1425 advisory.

    In libexpat before 2.7.4, the doContent function does not properly determine the buffer size bufSize     because there is no integer overflow check for tag buffer reallocation. (CVE-2026-25210)

Tenable has extracted the preceding description block directly from the tested product 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 version of FreeBSD installed on the remote host is prior to tested version. It is, therefore, affected by multiple vulnerabilities as referenced in the 027c6c07-065b-11f1-baae-589cfc023192 advisory.

    expat team reports:
    Update contains 2 security fixes:

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 remote Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS / 22.04 LTS / 24.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-8023-1 advisory.

    It was discovered that Expat, contained within the xmltok library, incorrectly handled the initialization     of parsers for external entities. An attacker could possibly use this issue to cause a denial of service.
    (CVE-2026-24515)

    It was discovered that Expat, contained within the xmltok library, incorrectly handled integer     calculations when allocating memory for XML tags. An attacker could possibly use this issue to cause a     denial of service or execute arbitrary code. (CVE-2026-25210)

Tenable has extracted the preceding description block directly from the Ubuntu 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 Ubuntu 14.04 LTS / 16.04 LTS / 18.04 LTS / 20.04 LTS / 22.04 LTS / 25.10 host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-8022-1 advisory.

    It was discovered that Expat incorrectly handled memory when parsing certain XML files. An attacker could     possibly use this issue to cause a denial of service. This issue was only addressed in Ubuntu 25.10.
    (CVE-2025-59375)

    It was discovered that Expat incorrectly handled the initialization of parsers for external entities. An     attacker could possibly use this issue to cause a denial of service. (CVE-2026-24515)

    It was discovered that Expat incorrectly handled integer calculations when allocating memory for XML tags.
    An attacker could possibly use this issue to cause a denial of service or execute arbitrary code.
    (CVE-2026-25210)

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

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

An update of the expat package has been released.

According to its self-reported version, the Tenable Nessus application running on the remote host prior to 10.10.2, 10.11.0 prior to 10.11.2. It is, therefore, affected by multiple vulnerabilities as referenced in the TNS-2026-04 advisory.

  - In libexpat before 2.7.4, XML_ExternalEntityParserCreate does not copy unknown encoding handler user data.
    (CVE-2026-24515)

  - In libexpat before 2.7.4, the doContent function does not properly determine the buffer size bufSize     because there is no integer overflow check for tag buffer reallocation. (CVE-2026-25210)

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 2.7.4. It is, therefore, affected by multiple vulnerabilities as referenced in the SSA:2026-031-01 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 Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - In libexpat before 2.7.4, the doContent function does not properly determine the buffer size bufSize     because there is no integer overflow check for tag buffer reallocation. (CVE-2026-25210)

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

ID	Name	Product	Family	Severity
299553	Amazon Linux 2 : firefox, --advisory ALAS2FIREFOX-2026-051 (ALASFIREFOX-2026-051)	Nessus	Amazon Linux Local Security Checks	high
299540	Amazon Linux 2023 : firefox (ALAS2023-2026-1424)	Nessus	Amazon Linux Local Security Checks	medium
299539	Amazon Linux 2 : thunderbird, --advisory ALAS2-2026-3171 (ALAS-2026-3171)	Nessus	Amazon Linux Local Security Checks	high
299537	Amazon Linux 2 : expat, --advisory ALAS2-2026-3170 (ALAS-2026-3170)	Nessus	Amazon Linux Local Security Checks	medium
299514	Amazon Linux 2023 : expat, expat-devel, expat-static (ALAS2023-2026-1425)	Nessus	Amazon Linux Local Security Checks	medium
298957	FreeBSD : expat -- multiple vulnerabilities (027c6c07-065b-11f1-baae-589cfc023192)	Nessus	FreeBSD Local Security Checks	low
298808	Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS / 22.04 LTS / 24.04 LTS : xmltok library vulnerabilities (USN-8023-1)	Nessus	Ubuntu Local Security Checks	low
298805	Ubuntu 14.04 LTS / 16.04 LTS / 18.04 LTS / 20.04 LTS / 22.04 LTS / 25.10 : Expat vulnerabilities (USN-8022-1)	Nessus	Ubuntu Local Security Checks	low
298353	Photon OS 5.0: Expat PHSA-2026-5.0-0756	Nessus	PhotonOS Local Security Checks	low
298226	Tenable Nessus < 10.10.2 / 10.11.0 < 10.11.2 Multiple Vulnerabilities (TNS-2026-04)	Nessus	Misc.	low
297491	Slackware Linux 15.0 / current expat Multiple Vulnerabilities (SSA:2026-031-01)	Nessus	Slackware Local Security Checks	low
297227	Linux Distros Unpatched Vulnerability : CVE-2026-25210	Nessus	Misc.	medium

Detections

Analytics

CVE-2026-25210

medium

Tenable Plugins

high

medium

high

medium

medium

low

low

low

low

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low

medium