Mitigation bypass in the DOM: postMessage component. This vulnerability was fixed in Firefox 150 and Thunderbird 150.

The remote Fedora 43 host has packages installed that are affected by multiple vulnerabilities as referenced in the FEDORA-2026-c0a4f03150 advisory.

    Update NSS to 3.122.1     Update to Firefox 150.0

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 FreeBSD installed on the remote host is prior to tested version. It is, therefore, affected by a vulnerability as referenced in the 61805c9e-4305-11f1-a627-b42e991fc52e advisory.

    https://bugzilla.mozilla.org/show_bug.cgi?id=1880429 reports:
    Mitigation bypass in the DOM: postMessage component.

Tenable has extracted the preceding description block directly from the FreeBSD 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 Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - Mitigation bypass in the DOM: postMessage component. This vulnerability was fixed in Firefox 150 and     Thunderbird 150. (CVE-2026-6755)

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

The remote Fedora 42 host has packages installed that are affected by multiple vulnerabilities as referenced in the FEDORA-2026-69538c9f7e advisory.

    Update NSS to 3.122.1     Update to Firefox 150.0

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 remote Fedora 44 host has packages installed that are affected by multiple vulnerabilities as referenced in the FEDORA-2026-fb08ad61f2 advisory.

    Update NSS to 3.122.1     Update to Firefox 150.0


    ----

    - New upstream release (149.0.2)

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 Windows host is prior to 150.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-33 advisory.

  - Incorrect boundary conditions, integer overflow in the Audio/Video: Playback component. This vulnerability     was fixed in Firefox 150 and Thunderbird 150. (CVE-2026-6783)

  - Use-after-free in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 150, Firefox ESR     115.35, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10. (CVE-2026-6746)

  - Use-after-free in the WebRTC component. This vulnerability was fixed in Firefox 150, Firefox ESR 140.10,     Thunderbird 150, and Thunderbird 140.10. (CVE-2026-6747)

  - Uninitialized memory in the Audio/Video: Web Codecs component. This vulnerability was fixed in Firefox     150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10. (CVE-2026-6748, CVE-2026-6751)

  - Information disclosure due to uninitialized memory in the Graphics: Canvas2D component. This vulnerability     was fixed in Firefox 150, Firefox ESR 115.35, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10.
    (CVE-2026-6749)

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 150.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-33 advisory.

  - Incorrect boundary conditions, integer overflow in the Audio/Video: Playback component. This vulnerability     was fixed in Firefox 150 and Thunderbird 150. (CVE-2026-6783)

  - Use-after-free in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 150, Firefox ESR     115.35, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10. (CVE-2026-6746)

  - Use-after-free in the WebRTC component. This vulnerability was fixed in Firefox 150, Firefox ESR 140.10,     Thunderbird 150, and Thunderbird 140.10. (CVE-2026-6747)

  - Uninitialized memory in the Audio/Video: Web Codecs component. This vulnerability was fixed in Firefox     150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10. (CVE-2026-6748, CVE-2026-6751)

  - Information disclosure due to uninitialized memory in the Graphics: Canvas2D component. This vulnerability     was fixed in Firefox 150, Firefox ESR 115.35, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10.
    (CVE-2026-6749)

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 150.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-30 advisory.

  - Incorrect boundary conditions, integer overflow in the Audio/Video: Playback component. This vulnerability     was fixed in Firefox 150 and Thunderbird 150. (CVE-2026-6783)

  - Use-after-free in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 150, Firefox ESR     115.35, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10. (CVE-2026-6746)

  - Use-after-free in the WebRTC component. This vulnerability was fixed in Firefox 150, Firefox ESR 140.10,     Thunderbird 150, and Thunderbird 140.10. (CVE-2026-6747)

  - Uninitialized memory in the Audio/Video: Web Codecs component. This vulnerability was fixed in Firefox     150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10. (CVE-2026-6748, CVE-2026-6751)

  - Information disclosure due to uninitialized memory in the Graphics: Canvas2D component. This vulnerability     was fixed in Firefox 150, Firefox ESR 115.35, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10.
    (CVE-2026-6749)

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 150.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-30 advisory.

  - Incorrect boundary conditions, integer overflow in the Audio/Video: Playback component. This vulnerability     was fixed in Firefox 150 and Thunderbird 150. (CVE-2026-6783)

  - Use-after-free in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 150, Firefox ESR     115.35, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10. (CVE-2026-6746)

  - Use-after-free in the WebRTC component. This vulnerability was fixed in Firefox 150, Firefox ESR 140.10,     Thunderbird 150, and Thunderbird 140.10. (CVE-2026-6747)

  - Uninitialized memory in the Audio/Video: Web Codecs component. This vulnerability was fixed in Firefox     150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10. (CVE-2026-6748, CVE-2026-6751)

  - Information disclosure due to uninitialized memory in the Graphics: Canvas2D component. This vulnerability     was fixed in Firefox 150, Firefox ESR 115.35, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10.
    (CVE-2026-6749)

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
312241	Fedora 43 : firefox / nss (2026-c0a4f03150)	Nessus	Fedora Local Security Checks	medium
311030	FreeBSD : Mozilla -- Mitigation bypass (61805c9e-4305-11f1-a627-b42e991fc52e)	Nessus	FreeBSD Local Security Checks	medium
310607	Linux Distros Unpatched Vulnerability : CVE-2026-6755	Nessus	Misc.	medium
310573	Fedora 42 : firefox / nss (2026-69538c9f7e)	Nessus	Fedora Local Security Checks	medium
310077	Fedora 44 : firefox / nss (2026-fb08ad61f2)	Nessus	Fedora Local Security Checks	medium
309100	Mozilla Thunderbird < 150.0	Nessus	Windows	medium
309098	Mozilla Thunderbird < 150.0	Nessus	MacOS X Local Security Checks	medium
307899	Mozilla Firefox < 150.0	Nessus	Windows	medium
307895	Mozilla Firefox < 150.0	Nessus	MacOS X Local Security Checks	medium

Detections

Analytics

CVE-2026-6755

medium

Tenable Plugins

medium

medium

medium

medium

medium

medium

medium

medium

medium