Privilege escalation in the DOM: Workers component. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.

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 151, Firefox     ESR 140.11, Thunderbird 151, and Thunderbird 140.11. (CVE-2026-8955)

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

The version of mozilla-firefox installed on the remote host is prior to 140.11.0esr. It is, therefore, affected by multiple vulnerabilities as referenced in the SSA:2026-139-02 advisory.

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

Tenable has extracted the preceding description block directly from the mozilla-firefox 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 140.11.0esr. It is, therefore, affected by multiple vulnerabilities as referenced in the SSA:2026-139-03 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 version of Thunderbird installed on the remote macOS or Mac OS X host is prior to 151.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-50 advisory.

  - Memory safety bugs present in Thunderbird 140.10 and Thunderbird 150. 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-2026-8974, CVE-2026-8975)

  - Incorrect boundary conditions in the Audio/Video: Web Codecs component. This vulnerability was fixed in     Firefox 151, Firefox ESR 115.36, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.
    (CVE-2026-8946)

  - Use-after-free in the DOM: Bindings (WebIDL) component. This vulnerability was fixed in Firefox 151,     Firefox ESR 115.36, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11. (CVE-2026-8947)

  - Same-origin policy bypass in the DOM: Networking component. This vulnerability was fixed in Firefox 151     and Thunderbird 151. (CVE-2026-8948)

  - Integer overflow in the Widget: Win32 component. This vulnerability was fixed in Firefox 151, Firefox ESR     140.11, Thunderbird 151, and Thunderbird 140.11. (CVE-2026-8949)

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 140.11. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-51 advisory.

  - Memory safety bugs present in Thunderbird 140.10 and Thunderbird 150. 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-2026-8974, CVE-2026-8975)

  - Incorrect boundary conditions in the Audio/Video: Web Codecs component. This vulnerability was fixed in     Firefox 151, Firefox ESR 115.36, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.
    (CVE-2026-8946)

  - Incorrect boundary conditions in the JavaScript Engine: JIT component. This vulnerability was fixed in     Firefox 150.0.3, Firefox ESR 115.36, Firefox ESR 140.11, and Thunderbird 140.11. (CVE-2026-8388)

  - Use-after-free in the DOM: Bindings (WebIDL) component. This vulnerability was fixed in Firefox 151,     Firefox ESR 115.36, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11. (CVE-2026-8947)

  - Other issue in the JavaScript Engine component. This vulnerability was fixed in Firefox 150.0.3, Firefox     ESR 115.36, Firefox ESR 140.11, and Thunderbird 140.11. (CVE-2026-8391)

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 151.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-50 advisory.

  - Memory safety bugs present in Thunderbird 140.10 and Thunderbird 150. 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-2026-8974, CVE-2026-8975)

  - Incorrect boundary conditions in the Audio/Video: Web Codecs component. This vulnerability was fixed in     Firefox 151, Firefox ESR 115.36, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.
    (CVE-2026-8946)

  - Use-after-free in the DOM: Bindings (WebIDL) component. This vulnerability was fixed in Firefox 151,     Firefox ESR 115.36, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11. (CVE-2026-8947)

  - Same-origin policy bypass in the DOM: Networking component. This vulnerability was fixed in Firefox 151     and Thunderbird 151. (CVE-2026-8948)

  - Integer overflow in the Widget: Win32 component. This vulnerability was fixed in Firefox 151, Firefox ESR     140.11, Thunderbird 151, and Thunderbird 140.11. (CVE-2026-8949)

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 140.11. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-51 advisory.

  - Memory safety bugs present in Thunderbird 140.10 and Thunderbird 150. 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-2026-8974, CVE-2026-8975)

  - Incorrect boundary conditions in the Audio/Video: Web Codecs component. This vulnerability was fixed in     Firefox 151, Firefox ESR 115.36, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.
    (CVE-2026-8946)

  - Incorrect boundary conditions in the JavaScript Engine: JIT component. This vulnerability was fixed in     Firefox 150.0.3, Firefox ESR 115.36, Firefox ESR 140.11, and Thunderbird 140.11. (CVE-2026-8388)

  - Use-after-free in the DOM: Bindings (WebIDL) component. This vulnerability was fixed in Firefox 151,     Firefox ESR 115.36, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11. (CVE-2026-8947)

  - Other issue in the JavaScript Engine component. This vulnerability was fixed in Firefox 150.0.3, Firefox     ESR 115.36, Firefox ESR 140.11, and Thunderbird 140.11. (CVE-2026-8391)

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 151.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-46 advisory.

  - Memory safety bugs present in Firefox ESR 115.35, Firefox ESR 140.10 and Firefox 150. 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-2026-8975)

  - Memory safety bugs present in Firefox 150. 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-2026-8973)

  - Memory safety bugs present in Firefox ESR 140.10 and Firefox 150. 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-2026-8974)

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 140.11. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-48 advisory.

  - Sandbox escape in the Profile Backup component. This vulnerability was fixed in Firefox 150.0.3, Firefox     ESR 115.36, and Firefox ESR 140.11. (CVE-2026-8401)

  - Incorrect boundary conditions in the JavaScript Engine: JIT component. This vulnerability was fixed in     Firefox 150.0.3, Firefox ESR 115.36, and Firefox ESR 140.11. (CVE-2026-8388)

  - Other issue in the JavaScript Engine component. This vulnerability was fixed in Firefox 150.0.3, Firefox     ESR 115.36, and Firefox ESR 140.11. (CVE-2026-8391)

  - Memory safety bugs present in Firefox ESR 140.10 and Firefox 150. 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-2026-8974)

  - Memory safety bugs present in Firefox ESR 115.35, Firefox ESR 140.10 and Firefox 150. 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-2026-8975)

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 140.11. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-48 advisory.

  - Sandbox escape in the Profile Backup component. This vulnerability was fixed in Firefox 150.0.3, Firefox     ESR 115.36, and Firefox ESR 140.11. (CVE-2026-8401)

  - Incorrect boundary conditions in the JavaScript Engine: JIT component. This vulnerability was fixed in     Firefox 150.0.3, Firefox ESR 115.36, and Firefox ESR 140.11. (CVE-2026-8388)

  - Other issue in the JavaScript Engine component. This vulnerability was fixed in Firefox 150.0.3, Firefox     ESR 115.36, and Firefox ESR 140.11. (CVE-2026-8391)

  - Memory safety bugs present in Firefox ESR 140.10 and Firefox 150. 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-2026-8974)

  - Memory safety bugs present in Firefox ESR 115.35, Firefox ESR 140.10 and Firefox 150. 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-2026-8975)

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 151.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-46 advisory.

  - Memory safety bugs present in Firefox ESR 115.35, Firefox ESR 140.10 and Firefox 150. 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-2026-8975)

  - Memory safety bugs present in Firefox 150. 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-2026-8973)

  - Memory safety bugs present in Firefox ESR 140.10 and Firefox 150. 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-2026-8974)

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	Severity
315529	Linux Distros Unpatched Vulnerability : CVE-2026-8955	Nessus	Misc.	medium
315522	Slackware Linux 15.0 / current mozilla-firefox Multiple Vulnerabilities (SSA:2026-139-02)	Nessus	Slackware Local Security Checks	critical
315520	Slackware Linux 15.0 / current mozilla-thunderbird Multiple Vulnerabilities (SSA:2026-139-03)	Nessus	Slackware Local Security Checks	critical
315434	Mozilla Thunderbird < 151.0	Nessus	MacOS X Local Security Checks	critical
315433	Mozilla Thunderbird < 140.11	Nessus	Windows	critical
315432	Mozilla Thunderbird < 151.0	Nessus	Windows	critical
315431	Mozilla Thunderbird < 140.11	Nessus	MacOS X Local Security Checks	critical
315327	Mozilla Firefox < 151.0	Nessus	MacOS X Local Security Checks	critical
315326	Mozilla Firefox ESR < 140.11	Nessus	MacOS X Local Security Checks	critical
315325	Mozilla Firefox ESR < 140.11	Nessus	Windows	critical
315323	Mozilla Firefox < 151.0	Nessus	Windows	critical

Detections

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CVE-2026-8955

medium

Tenable Plugins

medium

critical

critical

critical

critical

critical

critical

critical

critical

critical

critical