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

  - Use-after-free 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-2026-74943)

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

The remote Debian 13 host has packages installed that are affected by multiple vulnerabilities as referenced in the dsa-6451 advisory.

    - -------------------------------------------------------------------------     Debian Security Advisory DSA-6451-1                   security@debian.org     https://www.debian.org/security/                       Moritz Muehlenhoff     August 19, 2026                       https://www.debian.org/security/faq
    - -------------------------------------------------------------------------

    Package        : firefox-esr     CVE ID         : CVE-2026-74934 CVE-2026-74935 CVE-2026-74936 CVE-2026-74939                      CVE-2026-74940 CVE-2026-74941 CVE-2026-74942 CVE-2026-74943                      CVE-2026-74944 CVE-2026-74945 CVE-2026-74946 CVE-2026-74948                      CVE-2026-74949 CVE-2026-74953 CVE-2026-74957 CVE-2026-74959                      CVE-2026-74960 CVE-2026-74962 CVE-2026-74963 CVE-2026-74964                      CVE-2026-74965 CVE-2026-74967 CVE-2026-74969 CVE-2026-74971                      CVE-2026-74972 CVE-2026-74973 CVE-2026-74974 CVE-2026-74976                      CVE-2026-74983 CVE-2026-74987 CVE-2026-74990

    Multiple security issues have been found in the Mozilla Firefox web     browser, which could potentially result in the execution of arbitrary     code, privilege escalation, information disclosure or bypass of the     same-origin policy.

    For the stable distribution (trixie), these problems have been fixed in     version 140.14.0esr-1~deb13u1.

    We recommend that you upgrade your firefox-esr packages.

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

    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 mozilla-thunderbird installed on the remote host is prior to 140.14.0esr. It is, therefore, affected by multiple vulnerabilities as referenced in the SSA:2026-231-02 advisory.

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

Tenable has extracted the preceding description block directly from the mozilla-thunderbird 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 RockyLinux 9 host has packages installed that are affected by multiple vulnerabilities as referenced in the RLSA-2026:58897 advisory.

    * firefox: thunderbird: Mitigation bypass in the Data Loss Prevention component (CVE-2026-74983)

    * firefox: thunderbird: Site isolation issue in the Graphics: CanvasWebGL component (CVE-2026-74934)

    * firefox: thunderbird: Privilege escalation in the Networking: Cookies component (CVE-2026-74953)

    * firefox: thunderbird: Internally found bugs fixed in Firefox ESR 140.14, Firefox ESR 153.1 and Firefox     154 (CVE-2026-74987)

    * firefox: thunderbird: Information disclosure in the Graphics component (CVE-2026-74948)

    * firefox: thunderbird: Use-after-free in the Graphics: ImageLib component (CVE-2026-74943)

    * firefox: thunderbird: Information disclosure in the DOM: UI Events & Focus Handling component     (CVE-2026-74971)

    * firefox: thunderbird: Privilege escalation in the Graphics: CanvasWebGL component (CVE-2026-74941)

    * firefox: Privilege escalation in the Shell Integration component (CVE-2026-74965)

    * firefox: thunderbird: Privilege escalation due to incorrect boundary conditions in the Graphics:
    CanvasWebGL component (CVE-2026-74946)

    * firefox: Race condition, use-after-free in the Graphics component (CVE-2026-74973)

    * firefox: thunderbird: Privilege escalation due to use-after-free in the Graphics: Canvas2D component     (CVE-2026-74949)

    * firefox: thunderbird: Internally found bugs fixed in Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR     153.1 and Firefox 154 (CVE-2026-74990)

    * firefox: thunderbird: Use-after-free in the JavaScript: WebAssembly component (CVE-2026-74936)

    * firefox: thunderbird: Use-after-free in the Graphics: Text component (CVE-2026-74940)

    * firefox: thunderbird: Site isolation issue in the WebExtensions component (CVE-2026-74960)

    * firefox: thunderbird: Use-after-free in the Layout: Text and Fonts component (CVE-2026-74969)

    * firefox: thunderbird: Mitigation bypass in the Storage: Cache API component (CVE-2026-74959)

    * firefox: thunderbird: JIT miscompilation in the JavaScript Engine: JIT component (CVE-2026-74976)

    * firefox: thunderbird: Same-origin policy bypass in the Graphics: ImageLib component (CVE-2026-74974)

    * firefox: thunderbird: Mitigation bypass in the Safe Browsing component (CVE-2026-74957)

    * firefox: thunderbird: Same-origin policy bypass in the Audio/Video: Playback component (CVE-2026-74967)

    * firefox: Privilege escalation in the Remote Settings Client component (CVE-2026-74942)

    * firefox: thunderbird: Privilege escalation in the DOM: Navigation component (CVE-2026-74939)

    * firefox: thunderbird: Information disclosure in the DOM: Push Subscriptions component (CVE-2026-74972)

    * firefox: thunderbird: Information disclosure in the Graphics: Text component (CVE-2026-74945)

    * firefox: thunderbird: Same-origin policy bypass in the Networking: Cookies component (CVE-2026-74963)

    * firefox: thunderbird: Use-after-free in the DOM: Core & HTML component (CVE-2026-74944)

    * firefox: Integer overflow in the Graphics component (CVE-2026-74964)

    * firefox: Site isolation issue in the Networking: Cookies component (CVE-2026-74962)

    * firefox: thunderbird: Privilege escalation in the DOM: Networking component (CVE-2026-74935)

Tenable has extracted the preceding description block directly from the RockyLinux 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 host has packages installed that are affected by multiple vulnerabilities as referenced in the SUSE-SU-2026:3683-1 advisory.

    Update to Firefox Extended Support Release 140.14.0 ESR.

    - MFSA 2026-74 (bsc#1274867):
      - CVE-2026-74934: Site isolation issue in the Graphics: CanvasWebGL component.
      - CVE-2026-74935: Privilege escalation in the DOM: Networking component.
      - CVE-2026-74936: Use-after-free in the JavaScript: WebAssembly component.
      - CVE-2026-74937: Use-after-free in the JavaScript: GC component.
      - CVE-2026-74938: Mitigation bypass in the JavaScript: GC component.
      - CVE-2026-74939: Privilege escalation in the DOM: Navigation component.
      - CVE-2026-74940: Use-after-free in the Graphics: Text component.
      - CVE-2026-74941: Privilege escalation in the Graphics: CanvasWebGL component.
      - CVE-2026-74942: Privilege escalation in the Remote Settings Client component.
      - CVE-2026-74943: Use-after-free in the Graphics: ImageLib component.
      - CVE-2026-74944: Use-after-free in the DOM: Core & HTML component.
      - CVE-2026-74945: Information disclosure in the Graphics: Text component.
      - CVE-2026-74946: Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL     component.
      - CVE-2026-74947: Privilege escalation due to invalid pointer in the Graphics component.
      - CVE-2026-74948: Information disclosure in the Graphics component.
      - CVE-2026-74949: Privilege escalation due to use-after-free in the Graphics: Canvas2D component.
      - CVE-2026-74950: Privilege escalation in the Downloads API component.
      - CVE-2026-74951: Clickjacking issue in Firefox for Android.
      - CVE-2026-74952: Privilege escalation in the Application Update component.
      - CVE-2026-74953: Privilege escalation in the Networking: Cookies component.
      - CVE-2026-74954: Information disclosure due to side-channel in the Storage: Cache API component.
      - CVE-2026-74955: Privilege escalation in the Request Handling component.
      - CVE-2026-74956: Same-origin policy bypass in the DOM: Service Workers component.
      - CVE-2026-74957: Mitigation bypass in the Safe Browsing component.
      - CVE-2026-74958: Information disclosure in the WebRTC component.
      - CVE-2026-74959: Mitigation bypass in the Storage: Cache API component.
      - CVE-2026-74960: Site isolation issue in the WebExtensions component.
      - CVE-2026-74961: Side-channel in the Web Audio component.
      - CVE-2026-74962: Site isolation issue in the Networking: Cookies component.
      - CVE-2026-74963: Same-origin policy bypass in the Networking: Cookies component.
      - CVE-2026-74964: Integer overflow in the Graphics component.
      - CVE-2026-74965: Privilege escalation in the Shell Integration component.
      - CVE-2026-74966: Information disclosure in the Form Autofill component.
      - CVE-2026-74967: Same-origin policy bypass in the Audio/Video: Playback component.
      - CVE-2026-74968: Site isolation issue in the Graphics: WebRender component.
      - CVE-2026-74969: Use-after-free in the Layout: Text and Fonts component.
      - CVE-2026-74970: Site isolation issue in the Graphics component.
      - CVE-2026-74971: Information disclosure in the DOM: UI Events & Focus Handling component.
      - CVE-2026-74972: Information disclosure in the DOM: Push Subscriptions component.
      - CVE-2026-74973: Race condition, use-after-free in the Graphics component.
      - CVE-2026-74974: Same-origin policy bypass in the Graphics: ImageLib component.
      - CVE-2026-74975: Spoofing issue in the Downloads component in Firefox for Android.
      - CVE-2026-74976: JIT miscompilation in the JavaScript Engine: JIT component.
      - CVE-2026-74977: Integer overflow in the Graphics component.
      - CVE-2026-74978: Clickjacking issue in the Widget component.
      - CVE-2026-74979: Mitigation bypass in the Add-ons Manager component.
      - CVE-2026-74980: Clickjacking issue in the Downloads component in Firefox for Android.
      - CVE-2026-74981: Site isolation issue in the Audio/Video: Web Codecs component.
      - CVE-2026-74982: Denial-of-service in the Widget component.
      - CVE-2026-74983: Mitigation bypass in the Data Loss Prevention component.
      - CVE-2026-74984: Race condition in the JavaScript Engine component.
      - CVE-2026-74985: Privilege escalation in the Enterprise Policies component.
      - CVE-2026-74986: Site isolation issue in the CSS Parsing and Computation component.
      - CVE-2026-74987: Internally found bugs fixed in Firefox ESR 140.14, Firefox ESR 153.1 and Firefox 154.
      - CVE-2026-74988: Internally found bugs fixed in Firefox ESR 153.1 and Firefox 154.
      - CVE-2026-74989: Internally found bugs fixed in Firefox 154.
      - CVE-2026-74990: Internally found bugs fixed in Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR     153.1 and         Firefox 154.
      - CVE-2026-75874: Sandbox escape in the Remote Settings Client component.

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 AlmaLinux 10 host has a package installed that is affected by multiple vulnerabilities as referenced in the ALSA-2026:58899 advisory.

    * firefox: thunderbird: Mitigation bypass in the Data Loss Prevention component (CVE-2026-74983)
      * firefox: thunderbird: Site isolation issue in the Graphics: CanvasWebGL component (CVE-2026-74934)
      * firefox: thunderbird: Privilege escalation in the Networking: Cookies component (CVE-2026-74953)
      * firefox: thunderbird: Internally found bugs fixed in Firefox ESR 140.14, Firefox ESR 153.1 and Firefox     154 (CVE-2026-74987)
      * firefox: thunderbird: Information disclosure in the Graphics component (CVE-2026-74948)
      * firefox: thunderbird: Use-after-free in the Graphics: ImageLib component (CVE-2026-74943)
      * firefox: thunderbird: Information disclosure in the DOM: UI Events & Focus Handling component     (CVE-2026-74971)
      * firefox: thunderbird: Privilege escalation in the Graphics: CanvasWebGL component (CVE-2026-74941)
      * firefox: Privilege escalation in the Shell Integration component (CVE-2026-74965)
      * firefox: thunderbird: Privilege escalation due to incorrect boundary conditions in the Graphics:
    CanvasWebGL component (CVE-2026-74946)
      * firefox: Race condition, use-after-free in the Graphics component (CVE-2026-74973)
      * firefox: thunderbird: Privilege escalation due to use-after-free in the Graphics: Canvas2D component     (CVE-2026-74949)
      * firefox: thunderbird: Internally found bugs fixed in Firefox ESR 115.39, Firefox ESR 140.14, Firefox     ESR 153.1 and Firefox 154 (CVE-2026-74990)
      * firefox: thunderbird: Use-after-free in the JavaScript: WebAssembly component (CVE-2026-74936)
      * firefox: thunderbird: Use-after-free in the Graphics: Text component (CVE-2026-74940)
      * firefox: thunderbird: Site isolation issue in the WebExtensions component (CVE-2026-74960)
      * firefox: thunderbird: Use-after-free in the Layout: Text and Fonts component (CVE-2026-74969)
      * firefox: thunderbird: Mitigation bypass in the Storage: Cache API component (CVE-2026-74959)
      * firefox: thunderbird: JIT miscompilation in the JavaScript Engine: JIT component (CVE-2026-74976)
      * firefox: thunderbird: Same-origin policy bypass in the Graphics: ImageLib component (CVE-2026-74974)
      * firefox: thunderbird: Mitigation bypass in the Safe Browsing component (CVE-2026-74957)
      * firefox: thunderbird: Same-origin policy bypass in the Audio/Video: Playback component     (CVE-2026-74967)
      * firefox: Privilege escalation in the Remote Settings Client component (CVE-2026-74942)
      * firefox: thunderbird: Privilege escalation in the DOM: Navigation component (CVE-2026-74939)
      * firefox: thunderbird: Information disclosure in the DOM: Push Subscriptions component (CVE-2026-74972)
      * firefox: thunderbird: Information disclosure in the Graphics: Text component (CVE-2026-74945)
      * firefox: thunderbird: Same-origin policy bypass in the Networking: Cookies component (CVE-2026-74963)
      * firefox: thunderbird: Use-after-free in the DOM: Core & HTML component (CVE-2026-74944)
      * firefox: Integer overflow in the Graphics component (CVE-2026-74964)
      * firefox: Site isolation issue in the Networking: Cookies component (CVE-2026-74962)
      * firefox: thunderbird: Privilege escalation in the DOM: Networking component (CVE-2026-74935)

Tenable has extracted the preceding description block directly from the AlmaLinux 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 Tencent Linux installed on the remote TencentOS Server 3 host is prior to tested version. It is, therefore, affected by multiple vulnerabilities as referenced in the TSSA-2026:0912 advisory.

    Package updates are available for TencentOS Server 3 that fix the following vulnerabilities:

    CVE-2026-74934:
    A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the     following issue:
    Site isolation issue in the Graphics: CanvasWebGL component

    CVE-2026-74935:
    A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the     following issue:
    Privilege escalation in the DOM: Networking component

    CVE-2026-74936:
    A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the     following issue:
    Use-after-free in the JavaScript: WebAssembly component

    CVE-2026-74939:
    A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the     following issue:
    Privilege escalation in the DOM: Navigation component

    CVE-2026-74940:
    A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the     following issue:
    Use-after-free in the Graphics: Text component

    CVE-2026-74941:
    A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the     following issue:
    Privilege escalation in the Graphics: CanvasWebGL component

    CVE-2026-74942:
    A flaw was found in Firefox. The Mozilla Foundation's Security Advisory describes the following issue:
    Privilege escalation in the Remote Settings Client component

    CVE-2026-74943:
    A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the     following issue:
    Use-after-free in the Graphics: ImageLib component

    CVE-2026-74944:
    A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the     following issue:
    Use-after-free in the DOM: Core & HTML component

    CVE-2026-74945:
    A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the     following issue:
    Information disclosure in the Graphics: Text component

    CVE-2026-74946:
    A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the     following issue:
    Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component

    CVE-2026-74948:
    A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the     following issue:
    Information disclosure in the Graphics component

    CVE-2026-74949:
    A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the     following issue:
    Privilege escalation due to use-after-free in the Graphics: Canvas2D component

    CVE-2026-74953:
    A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the     following issue:
    Privilege escalation in the Networking: Cookies component

    CVE-2026-74957:
    A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the     following issue:
    Mitigation bypass in the Safe Browsing component

    CVE-2026-74959:
    A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the     following issue:
    Mitigation bypass in the Storage: Cache API component

    CVE-2026-74960:
    A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the     following issue:
    Site isolation issue in the WebExtensions component

    CVE-2026-74962:
    A flaw was found in Firefox. The Mozilla Foundation's Security Advisory describes the following issue:
    Site isolation issue in the Networking: Cookies component

    CVE-2026-74963:
    A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the     following issue:
    Same-origin policy bypass in the Networking: Cookies component

    CVE-2026-74964:
    A flaw was found in Firefox. The Mozilla Foundation's Security Advisory describes the following issue:
    Integer overflow in the Graphics component

    CVE-2026-74965:
    A flaw was found in Firefox. The Mozilla Foundation's Security Advisory describes the following issue:
    Privilege escalation in the Shell Integration component

    CVE-2026-74967:
    A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the     following issue:
    Same-origin policy bypass in the Audio/Video: Playback component

    CVE-2026-74969:
    A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the     following issue:
    Use-after-free in the Layout: Text and Fonts component

    CVE-2026-74971:
    A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the     following issue:
    Information disclosure in the DOM: UI Events & Focus Handling component

    CVE-2026-74972:
    A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the     following issue:
    Information disclosure in the DOM: Push Subscriptions component

    CVE-2026-74973:
    A flaw was found in Firefox. The Mozilla Foundation's Security Advisory describes the following issue:
    Race condition, use-after-free in the Graphics component

    CVE-2026-74974:
    A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the     following issue:
    Same-origin policy bypass in the Graphics: ImageLib component

    CVE-2026-74976:
    A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the     following issue:
    JIT miscompilation in the JavaScript Engine: JIT component

    CVE-2026-74983:
    A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the     following issue:
    Mitigation bypass in the Data Loss Prevention component

    CVE-2026-74987:
    A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the     following issue:
    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.

    CVE-2026-74990:
    A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the     following issue:
    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.

Tenable has extracted the preceding description block directly from the Tencent Linux 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 remote Redhat Enterprise Linux 9 host has a package installed that is affected by multiple vulnerabilities as referenced in the RHSA-2026:65766 advisory.

    Mozilla Thunderbird is a standalone mail and newsgroup client.

    Security Fix(es):

    * firefox: thunderbird: Site isolation issue in the Graphics: CanvasWebGL component (CVE-2026-74934)

    * firefox: thunderbird: Internally found bugs fixed in Firefox ESR 140.14, Firefox ESR 153.1 and Firefox     154 (CVE-2026-74987)

    * firefox: thunderbird: Use-after-free in the Graphics: ImageLib component (CVE-2026-74943)

    * firefox: thunderbird: Information disclosure in the DOM: UI Events & Focus Handling component     (CVE-2026-74971)

    * firefox: Privilege escalation in the Shell Integration component (CVE-2026-74965)

    * firefox: thunderbird: Privilege escalation due to incorrect boundary conditions in the Graphics:
    CanvasWebGL component (CVE-2026-74946)

    * firefox: Race condition, use-after-free in the Graphics component (CVE-2026-74973)

    * firefox: thunderbird: Privilege escalation due to use-after-free in the Graphics: Canvas2D component     (CVE-2026-74949)

    * firefox: thunderbird: Internally found bugs fixed in Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR     153.1 and Firefox 154 (CVE-2026-74990)

    * firefox: thunderbird: Use-after-free in the Graphics: Text component (CVE-2026-74940)

    * firefox: thunderbird: Site isolation issue in the WebExtensions component (CVE-2026-74960)

    * firefox: thunderbird: Mitigation bypass in the Storage: Cache API component (CVE-2026-74959)

    * firefox: thunderbird: JIT miscompilation in the JavaScript Engine: JIT component (CVE-2026-74976)

    * firefox: thunderbird: Same-origin policy bypass in the Graphics: ImageLib component (CVE-2026-74974)

    * firefox: thunderbird: Mitigation bypass in the Safe Browsing component (CVE-2026-74957)

    * firefox: Privilege escalation in the Remote Settings Client component (CVE-2026-74942)

    * firefox: thunderbird: Privilege escalation in the DOM: Navigation component (CVE-2026-74939)

    * firefox: thunderbird: Information disclosure in the DOM: Push Subscriptions component (CVE-2026-74972)

    * firefox: thunderbird: Information disclosure in the Graphics: Text component (CVE-2026-74945)

    * firefox: thunderbird: Same-origin policy bypass in the Networking: Cookies component (CVE-2026-74963)

    * firefox: thunderbird: Use-after-free in the DOM: Core & HTML component (CVE-2026-74944)

    * firefox: Site isolation issue in the Networking: Cookies component (CVE-2026-74962)

    * firefox: thunderbird: Privilege escalation in the DOM: Networking component (CVE-2026-74935)

    For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and     other related information, refer to the CVE page(s) listed in the References section.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.

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

ID	Name	Product	Family	Published	Updated	Severity
337918	Linux Distros Unpatched Vulnerability : CVE-2026-74943	Nessus	Misc.	8/19/2026	9/8/2026	critical
338126	Debian dsa-6451 : firefox-esr - security update	Nessus	Debian Local Security Checks	8/19/2026	8/24/2026	critical
338218	Slackware Linux 15.0 / current mozilla-thunderbird Multiple Vulnerabilities (SSA:2026-231-02)	Nessus	Slackware Local Security Checks	8/20/2026	8/24/2026	critical
339414	RockyLinux 9 : firefox (RLSA-2026:58897)	Nessus	Rocky Linux Local Security Checks	8/25/2026	8/28/2026	critical
339734	SUSE SLES12: MozillaFirefox / MozillaFirefox-devel / etc (SUSE-SU-2026:3683-1)	Nessus	SuSE Local Security Checks	8/26/2026	8/28/2026	critical
340752	AlmaLinux 10 : firefox (ALSA-2026:58899)	Nessus	Alma Linux Local Security Checks	8/26/2026	8/28/2026	critical
341101	TencentOS Server 3: firefox (TSSA-2026:0912)	Nessus	Tencent Local Security Checks	8/27/2026	8/27/2026	critical
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
342669	openSUSE 16: MozillaFirefox / MozillaFirefox-branding-upstream / etc (openSUSE-SU-2026:21713-1)	Nessus	SuSE Local Security Checks	9/3/2026	9/3/2026	critical
343998	RHEL 9 : thunderbird (RHSA-2026:65766)	Nessus	Red Hat Local Security Checks	9/9/2026	9/9/2026	critical

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