Privilege escalation in the DOM: Workers component. This vulnerability was fixed in Firefox 153, Thunderbird 153, Firefox ESR 140.15, and Thunderbird 140.15.

The version of Thunderbird installed on the remote Windows host is prior to 140.15. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-87 advisory.

  - Privilege escalation due to invalid pointer in the Graphics component. This vulnerability was fixed in     Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird     140.15, and Thunderbird 153.2. (CVE-2026-84131)

  - Sandbox escape in the Remote Settings Client component. This vulnerability was fixed in Firefox 154,     Thunderbird 154, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 140.15, and     Thunderbird 153.2. (CVE-2026-75874)

  - Triggering an error condition in certain MIME bodies would cause uninitialized memory to be used.
    (CVE-2026-84639)

  - A maliciously constructed mail header could lead to a one byte read past the end of a buffer.
    (CVE-2026-84640)

  - A malicious IMAP server can trigger use-after-free and heap-memory disclosure by sending a crafted ID     response. Heap contents can ultimately be persisted to prefs.js. (CVE-2026-84641)

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 macOS or Mac OS X host is prior to 140.15. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-87 advisory.

  - Privilege escalation due to invalid pointer in the Graphics component. This vulnerability was fixed in     Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird     140.15, and Thunderbird 153.2. (CVE-2026-84131)

  - Sandbox escape in the Remote Settings Client component. This vulnerability was fixed in Firefox 154,     Thunderbird 154, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 140.15, and     Thunderbird 153.2. (CVE-2026-75874)

  - Triggering an error condition in certain MIME bodies would cause uninitialized memory to be used.
    (CVE-2026-84639)

  - A maliciously constructed mail header could lead to a one byte read past the end of a buffer.
    (CVE-2026-84640)

  - A malicious IMAP server can trigger use-after-free and heap-memory disclosure by sending a crafted ID     response. Heap contents can ultimately be persisted to prefs.js. (CVE-2026-84641)

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

The version of Firefox ESR installed on the remote macOS or Mac OS X host is prior to 140.15. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-84 advisory.

  - Sandbox escape in the Remote Settings Client component. This vulnerability was fixed in Firefox 154 and     Thunderbird 154. (CVE-2026-75874)

  - Privilege escalation in the DOM: Workers component. This vulnerability was fixed in Firefox 153,     Thunderbird 153, and Firefox ESR 140.15. (CVE-2026-16365)

  - Use-after-free in the Audio/Video component. This vulnerability was fixed in Firefox 155, Firefox ESR     115.40, Firefox ESR 140.15, and Firefox ESR 153.2. (CVE-2026-84120)

  - Use-after-free in the Audio/Video component. This vulnerability was fixed in Firefox 155, Firefox ESR     140.15, and Firefox ESR 153.2. (CVE-2026-84122)

  - Privilege escalation in the DOM: Navigation component. This vulnerability was fixed in Firefox 153,     Firefox ESR 140.13, Thunderbird 153, Thunderbird 140.13, and Firefox ESR 140.15. (CVE-2026-16371)

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

The version of Firefox ESR installed on the remote Windows host is prior to 140.15. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-84 advisory.

  - Sandbox escape in the Remote Settings Client component. This vulnerability was fixed in Firefox 154 and     Thunderbird 154. (CVE-2026-75874)

  - Privilege escalation in the DOM: Workers component. This vulnerability was fixed in Firefox 153,     Thunderbird 153, and Firefox ESR 140.15. (CVE-2026-16365)

  - Use-after-free in the Audio/Video component. This vulnerability was fixed in Firefox 155, Firefox ESR     115.40, Firefox ESR 140.15, and Firefox ESR 153.2. (CVE-2026-84120)

  - Use-after-free in the Audio/Video component. This vulnerability was fixed in Firefox 155, Firefox ESR     140.15, and Firefox ESR 153.2. (CVE-2026-84122)

  - Privilege escalation in the DOM: Navigation component. This vulnerability was fixed in Firefox 153,     Firefox ESR 140.13, Thunderbird 153, Thunderbird 140.13, and Firefox ESR 140.15. (CVE-2026-16371)

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

The remote Fedora 43 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-6dab7a3eff advisory.

    - Update to latest upstream (153.0)

    ----

    - New upstream release (153.0)

    ----

    - Updated to latest upstream (153.0)

Tenable has extracted the preceding description block directly from the Fedora 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.

  - Privilege escalation in the DOM: Workers component. This vulnerability was fixed in Firefox 153 and     Thunderbird 153. (CVE-2026-16365)

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

The remote Fedora 44 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-7d71f89d7e advisory.

    - Update to latest upstream (153.0)

    ----

    - New upstream release (153.0)

    ----

    - Updated to latest upstream (153.0)

Tenable has extracted the preceding description block directly from the Fedora 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 macOS or Mac OS X host is prior to 153.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-71 advisory.

  - Memory safety bugs present in Thunderbird ESR 140.12 and Thunderbird 152. Some of these bugs showed     evidence of memory corruption and we presume that with enough effort some of these could have been     exploited to run arbitrary code. (CVE-2026-16360, CVE-2026-16412)

  - Sandbox escape due to invalid pointer in the Disability Access APIs component. This vulnerability was     fixed in Firefox 153 and Thunderbird 153. (CVE-2026-16367)

  - The code to parse MIME headers for display when forwarding a message (if the setting to view all headers     was enabled) had an off-by-one error, allowing a single byte to be read from the memory after the buffer     for the headers, and potentially crashing Thunderbird. (CVE-2026-14899)

  - Same-origin policy bypass in the DOM: Navigation component. This vulnerability was fixed in Firefox 153,     Firefox ESR 115.38, Firefox ESR 140.13, Thunderbird 153, and Thunderbird 140.13. (CVE-2026-16349)

  - Incorrect boundary conditions in the Audio/Video: cubeb component. This vulnerability was fixed in Firefox     153, Firefox ESR 115.38, Firefox ESR 140.13, Thunderbird 153, and Thunderbird 140.13. (CVE-2026-16350)

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 Windows host is prior to 153.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-71 advisory.

  - Memory safety bugs present in Thunderbird ESR 140.12 and Thunderbird 152. Some of these bugs showed     evidence of memory corruption and we presume that with enough effort some of these could have been     exploited to run arbitrary code. (CVE-2026-16360, CVE-2026-16412)

  - Sandbox escape due to invalid pointer in the Disability Access APIs component. This vulnerability was     fixed in Firefox 153 and Thunderbird 153. (CVE-2026-16367)

  - The code to parse MIME headers for display when forwarding a message (if the setting to view all headers     was enabled) had an off-by-one error, allowing a single byte to be read from the memory after the buffer     for the headers, and potentially crashing Thunderbird. (CVE-2026-14899)

  - Same-origin policy bypass in the DOM: Navigation component. This vulnerability was fixed in Firefox 153,     Firefox ESR 115.38, Firefox ESR 140.13, Thunderbird 153, and Thunderbird 140.13. (CVE-2026-16349)

  - Incorrect boundary conditions in the Audio/Video: cubeb component. This vulnerability was fixed in Firefox     153, Firefox ESR 115.38, Firefox ESR 140.13, Thunderbird 153, and Thunderbird 140.13. (CVE-2026-16350)

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

The version of Firefox installed on the remote macOS or Mac OS X host is prior to 153.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-68 advisory.

  - Memory safety bugs present in Firefox ESR 140.12 and Firefox 152. Some of these bugs showed evidence of     memory corruption and we presume that with enough effort some of these could have been exploited to run     arbitrary code. (CVE-2026-16412)

  - Sandbox escape due to invalid pointer in the Disability Access APIs component. This vulnerability was     fixed in Firefox 153 and Thunderbird 153. (CVE-2026-16367)

  - Same-origin policy bypass in the DOM: Navigation component. This vulnerability was fixed in Firefox 153,     Firefox ESR 115.38, Firefox ESR 140.13, Thunderbird 153, and Thunderbird 140.13. (CVE-2026-16349)

  - Incorrect boundary conditions in the Audio/Video: cubeb component. This vulnerability was fixed in Firefox     153, Firefox ESR 115.38, Firefox ESR 140.13, Thunderbird 153, and Thunderbird 140.13. (CVE-2026-16350)

  - Use-after-free in the WebRTC: Audio/Video component. This vulnerability was fixed in Firefox 153, Firefox     ESR 140.13, Thunderbird 153, and Thunderbird 140.13. (CVE-2026-16362)

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

The version of Firefox installed on the remote Windows host is prior to 153.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-68 advisory.

  - Memory safety bugs present in Firefox ESR 140.12 and Firefox 152. Some of these bugs showed evidence of     memory corruption and we presume that with enough effort some of these could have been exploited to run     arbitrary code. (CVE-2026-16412)

  - Sandbox escape due to invalid pointer in the Disability Access APIs component. This vulnerability was     fixed in Firefox 153 and Thunderbird 153. (CVE-2026-16367)

  - Same-origin policy bypass in the DOM: Navigation component. This vulnerability was fixed in Firefox 153,     Firefox ESR 115.38, Firefox ESR 140.13, Thunderbird 153, and Thunderbird 140.13. (CVE-2026-16349)

  - Incorrect boundary conditions in the Audio/Video: cubeb component. This vulnerability was fixed in Firefox     153, Firefox ESR 115.38, Firefox ESR 140.13, Thunderbird 153, and Thunderbird 140.13. (CVE-2026-16350)

  - Use-after-free in the WebRTC: Audio/Video component. This vulnerability was fixed in Firefox 153, Firefox     ESR 140.13, Thunderbird 153, and Thunderbird 140.13. (CVE-2026-16362)

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	Type	Severity
342258	Mozilla Thunderbird < 140.15	Nessus	Windows	Local	critical
342257	Mozilla Thunderbird < 140.15	Nessus	MacOS X Local Security Checks	Local	critical
342132	Mozilla Firefox ESR < 140.15	Nessus	MacOS X Local Security Checks	Local	critical
342131	Mozilla Firefox ESR < 140.15	Nessus	Windows	Local	critical
329998	Fedora 43 : firefox (2026-6dab7a3eff)	Nessus	Fedora Local Security Checks	Local	critical
329436	Linux Distros Unpatched Vulnerability : CVE-2026-16365	Nessus	Misc.	Local	high
329269	Fedora 44 : firefox (2026-7d71f89d7e)	Nessus	Fedora Local Security Checks	Local	critical
329090	Mozilla Thunderbird < 153.0	Nessus	MacOS X Local Security Checks	Local	critical
329088	Mozilla Thunderbird < 153.0	Nessus	Windows	Local	critical
328774	Mozilla Firefox < 153.0	Nessus	MacOS X Local Security Checks	Local	critical
328773	Mozilla Firefox < 153.0	Nessus	Windows	Local	critical

Detections

Analytics

CVE-2026-16365

high

Tenable Plugins

critical

critical

critical

critical

critical

high

critical

critical

critical

critical

critical