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.

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

  - 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)

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

The version of Thunderbird installed on the remote Windows host is prior to 153.1. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-80 advisory.

  - 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-2026-74987, CVE-2026-74990)

  - Site isolation issue in the Graphics: CanvasWebGL 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-2026-74934)

  - Privilege escalation in the DOM: Networking 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-2026-74935)

  - Use-after-free in the JavaScript: WebAssembly 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-2026-74936)

  - Use-after-free in the JavaScript: GC component. This vulnerability was fixed in Firefox 154, Firefox ESR     153.1, Thunderbird 154, and Thunderbird 153.1. (CVE-2026-74937)

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 154.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-78 advisory.

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

  - Site isolation issue in the Graphics: CanvasWebGL 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-2026-74934)

  - Privilege escalation in the DOM: Networking 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-2026-74935)

  - Use-after-free in the JavaScript: WebAssembly 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-2026-74936)

  - Use-after-free in the JavaScript: GC component. This vulnerability was fixed in Firefox 154, Firefox ESR     153.1, Thunderbird 154, and Thunderbird 153.1. (CVE-2026-74937)

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 154.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-78 advisory.

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

  - Site isolation issue in the Graphics: CanvasWebGL 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-2026-74934)

  - Privilege escalation in the DOM: Networking 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-2026-74935)

  - Use-after-free in the JavaScript: WebAssembly 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-2026-74936)

  - Use-after-free in the JavaScript: GC component. This vulnerability was fixed in Firefox 154, Firefox ESR     153.1, Thunderbird 154, and Thunderbird 153.1. (CVE-2026-74937)

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 140.14. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-79 advisory.

  - 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-2026-74987, CVE-2026-74990)

  - Site isolation issue in the Graphics: CanvasWebGL 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-2026-74934)

  - Privilege escalation in the DOM: Networking 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-2026-74935)

  - Use-after-free in the JavaScript: WebAssembly 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-2026-74936)

  - 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)

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 140.14. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-79 advisory.

  - 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-2026-74987, CVE-2026-74990)

  - Site isolation issue in the Graphics: CanvasWebGL 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-2026-74934)

  - Privilege escalation in the DOM: Networking 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-2026-74935)

  - Use-after-free in the JavaScript: WebAssembly 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-2026-74936)

  - 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)

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 153.1. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-80 advisory.

  - 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-2026-74987, CVE-2026-74990)

  - Site isolation issue in the Graphics: CanvasWebGL 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-2026-74934)

  - Privilege escalation in the DOM: Networking 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-2026-74935)

  - Use-after-free in the JavaScript: WebAssembly 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-2026-74936)

  - Use-after-free in the JavaScript: GC component. This vulnerability was fixed in Firefox 154, Firefox ESR     153.1, Thunderbird 154, and Thunderbird 153.1. (CVE-2026-74937)

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 140.14. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-76 advisory.

  - Internally found bugs present in Firefox ESR 115.38, Firefox ESR 140.13, Firefox ESR 153.0 and Firefox     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)

  - Internally found bugs present in Firefox ESR 140.13, Firefox ESR 153.0 and Firefox 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-2026-74987)

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 154.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-74 advisory.

  - Internally found bugs present in Firefox ESR 115.38, Firefox ESR 140.13, Firefox ESR 153.0 and Firefox     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)

  - Internally found bugs present in Firefox ESR 140.13, Firefox ESR 153.0 and Firefox 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-2026-74987)

  - Internally found bugs present in Firefox ESR 153.0 and Firefox 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-2026-74988)

  - Internally found bugs present in Firefox 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-2026-74989)

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 153.1. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-77 advisory.

  - Internally found bugs present in Firefox ESR 115.38, Firefox ESR 140.13, Firefox ESR 153.0 and Firefox     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)

  - Internally found bugs present in Firefox ESR 140.13, Firefox ESR 153.0 and Firefox 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-2026-74987)

  - Internally found bugs present in Firefox ESR 153.0 and Firefox 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-2026-74988)

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 153.1. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-77 advisory.

  - Internally found bugs present in Firefox ESR 115.38, Firefox ESR 140.13, Firefox ESR 153.0 and Firefox     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)

  - Internally found bugs present in Firefox ESR 140.13, Firefox ESR 153.0 and Firefox 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-2026-74987)

  - Internally found bugs present in Firefox ESR 153.0 and Firefox 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-2026-74988)

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 154.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-74 advisory.

  - Internally found bugs present in Firefox ESR 115.38, Firefox ESR 140.13, Firefox ESR 153.0 and Firefox     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)

  - Internally found bugs present in Firefox ESR 140.13, Firefox ESR 153.0 and Firefox 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-2026-74987)

  - Internally found bugs present in Firefox ESR 153.0 and Firefox 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-2026-74988)

  - Internally found bugs present in Firefox 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-2026-74989)

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 140.14. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-76 advisory.

  - Internally found bugs present in Firefox ESR 115.38, Firefox ESR 140.13, Firefox ESR 153.0 and Firefox     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)

  - Internally found bugs present in Firefox ESR 140.13, Firefox ESR 153.0 and Firefox 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-2026-74987)

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
337948	Linux Distros Unpatched Vulnerability : CVE-2026-74987	Nessus	Misc.	Local	critical
337890	Mozilla Thunderbird < 153.1	Nessus	Windows	Local	critical
337889	Mozilla Thunderbird < 154.0	Nessus	MacOS X Local Security Checks	Local	critical
337888	Mozilla Thunderbird < 154.0	Nessus	Windows	Local	critical
337887	Mozilla Thunderbird < 140.14	Nessus	MacOS X Local Security Checks	Local	critical
337886	Mozilla Thunderbird < 140.14	Nessus	Windows	Local	critical
337885	Mozilla Thunderbird < 153.1	Nessus	MacOS X Local Security Checks	Local	critical
337630	Mozilla Firefox ESR < 140.14	Nessus	MacOS X Local Security Checks	Local	critical
337629	Mozilla Firefox < 154.0	Nessus	Windows	Local	critical
337628	Mozilla Firefox ESR < 153.1	Nessus	Windows	Local	critical
337627	Mozilla Firefox ESR < 153.1	Nessus	MacOS X Local Security Checks	Local	critical
337625	Mozilla Firefox < 154.0	Nessus	MacOS X Local Security Checks	Local	critical
337624	Mozilla Firefox ESR < 140.14	Nessus	Windows	Local	critical

Detections

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CVE-2026-74987

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