Spoofing issue in the Privacy: Anti-Tracking component. This vulnerability was fixed in Firefox 149 and Thunderbird 149.

The remote Fedora 42 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-a026a1b0c5 advisory.

    - Fix blurry popups on some fraction scales (mzbz#2019668)

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 42 host has packages installed that are affected by multiple vulnerabilities as referenced in the FEDORA-2026-49237e1ced advisory.

    Update NSS to 3.121.0     Update to Firefox 149.0

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.

  - Spoofing issue in the Privacy: Anti-Tracking component. This vulnerability affects Firefox < 149 and     Thunderbird < 149. (CVE-2026-4728)

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

The version of FreeBSD installed on the remote host is prior to tested version. It is, therefore, affected by multiple vulnerabilities as referenced in the 26c24872-2943-11f1-8461-b42e991fc52e advisory.

    CVE-2026-4729: Memory safety bugs     CVE-2026-4728: Spoofing issue in the Privacy: Anti-Tracking             component.
    CVE-2026-4727: Denial-of-service in the Libraries component             in NSS.
    CVE-2026-4726: Denial-of-service in the XML component.
    CVE-2026-4725: Sandbox escape due to use-after-free in the             Graphics: Canvas2D component.
    CVE-2026-4724: Undefined behavior in the Audio/Video             component.
    CVE-2026-4723: Use-after-free in the JavaScript Engine             component.
    CVE-2026-4722: Privilege escalation in the IPC component.

Tenable has extracted the preceding description block directly from the FreeBSD 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 43 host has packages installed that are affected by multiple vulnerabilities as referenced in the FEDORA-2026-d8099dd719 advisory.

    Update NSS to 3.121.0     Update to Firefox 149.0

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 Windows host is prior to 149.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-23 advisory.

  - Sandbox escape due to use-after-free in the Graphics: Canvas2D component. This vulnerability affects     Firefox < 149 and Thunderbird < 149. (CVE-2026-4725)

  - Spoofing issue in Thunderbird. This vulnerability affects Thunderbird < 149 and Thunderbird < 140.9.
    (CVE-2026-3889)

  - A malicious mail server could send malformed strings with negative lengths, causing the parser to read     memory outside the buffer. If a mail server or connection to a mail server were compromised, an attacker     could cause the parser to malfunction, potentially crashing Thunderbird or leaking sensitive data.
    (CVE-2026-4371)

  - Race condition, use-after-free in the Graphics: WebRender component. This vulnerability affects Firefox <     149, Firefox ESR < 115.34, Firefox ESR < 140.9, Thunderbird < 149, and Thunderbird < 140.9.
    (CVE-2026-4684)

  - Incorrect boundary conditions in the Graphics: Canvas2D component. This vulnerability affects Firefox <     149, Firefox ESR < 115.34, Firefox ESR < 140.9, Thunderbird < 149, and Thunderbird < 140.9.
    (CVE-2026-4685, CVE-2026-4686, CVE-2026-4706, CVE-2026-4707)

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 149.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-23 advisory.

  - Sandbox escape due to use-after-free in the Graphics: Canvas2D component. This vulnerability affects     Firefox < 149 and Thunderbird < 149. (CVE-2026-4725)

  - Spoofing issue in Thunderbird. This vulnerability affects Thunderbird < 149 and Thunderbird < 140.9.
    (CVE-2026-3889)

  - A malicious mail server could send malformed strings with negative lengths, causing the parser to read     memory outside the buffer. If a mail server or connection to a mail server were compromised, an attacker     could cause the parser to malfunction, potentially crashing Thunderbird or leaking sensitive data.
    (CVE-2026-4371)

  - Race condition, use-after-free in the Graphics: WebRender component. This vulnerability affects Firefox <     149, Firefox ESR < 115.34, Firefox ESR < 140.9, Thunderbird < 149, and Thunderbird < 140.9.
    (CVE-2026-4684)

  - Incorrect boundary conditions in the Graphics: Canvas2D component. This vulnerability affects Firefox <     149, Firefox ESR < 115.34, Firefox ESR < 140.9, Thunderbird < 149, and Thunderbird < 140.9.
    (CVE-2026-4685, CVE-2026-4686, CVE-2026-4706, CVE-2026-4707)

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 149.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-20 advisory.

  - Sandbox escape due to use-after-free in the Graphics: Canvas2D component. This vulnerability affects     Firefox < 149 and Thunderbird < 149. (CVE-2026-4725)

  - Race condition, use-after-free in the Graphics: WebRender component. This vulnerability affects Firefox <     149, Firefox ESR < 115.34, Firefox ESR < 140.9, Thunderbird < 149, and Thunderbird < 140.9.
    (CVE-2026-4684)

  - Incorrect boundary conditions in the Graphics: Canvas2D component. This vulnerability affects Firefox <     149, Firefox ESR < 115.34, Firefox ESR < 140.9, Thunderbird < 149, and Thunderbird < 140.9.
    (CVE-2026-4685, CVE-2026-4686, CVE-2026-4706, CVE-2026-4707)

  - Sandbox escape due to incorrect boundary conditions in the Telemetry component. This vulnerability affects     Firefox < 149, Firefox ESR < 115.34, Firefox ESR < 140.9, Thunderbird < 149, and Thunderbird < 140.9.
    (CVE-2026-4687)

  - Sandbox escape due to use-after-free in the Disability Access APIs component. This vulnerability affects     Firefox < 149, Firefox ESR < 140.9, Thunderbird < 149, and Thunderbird < 140.9. (CVE-2026-4688)

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 149.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-20 advisory.

  - Sandbox escape due to use-after-free in the Graphics: Canvas2D component. This vulnerability affects     Firefox < 149 and Thunderbird < 149. (CVE-2026-4725)

  - Race condition, use-after-free in the Graphics: WebRender component. This vulnerability affects Firefox <     149, Firefox ESR < 115.34, Firefox ESR < 140.9, Thunderbird < 149, and Thunderbird < 140.9.
    (CVE-2026-4684)

  - Incorrect boundary conditions in the Graphics: Canvas2D component. This vulnerability affects Firefox <     149, Firefox ESR < 115.34, Firefox ESR < 140.9, Thunderbird < 149, and Thunderbird < 140.9.
    (CVE-2026-4685, CVE-2026-4686, CVE-2026-4706, CVE-2026-4707)

  - Sandbox escape due to incorrect boundary conditions in the Telemetry component. This vulnerability affects     Firefox < 149, Firefox ESR < 115.34, Firefox ESR < 140.9, Thunderbird < 149, and Thunderbird < 140.9.
    (CVE-2026-4687)

  - Sandbox escape due to use-after-free in the Disability Access APIs component. This vulnerability affects     Firefox < 149, Firefox ESR < 140.9, Thunderbird < 149, and Thunderbird < 140.9. (CVE-2026-4688)

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
304448	Fedora 42 : firefox (2026-a026a1b0c5)	Nessus	Fedora Local Security Checks	critical
304408	Fedora 42 : firefox / nss (2026-49237e1ced)	Nessus	Fedora Local Security Checks	critical
304115	Linux Distros Unpatched Vulnerability : CVE-2026-4728	Nessus	Misc.	medium
303888	FreeBSD : Mozilla -- Multiple vulnerabilities (26c24872-2943-11f1-8461-b42e991fc52e)	Nessus	FreeBSD Local Security Checks	critical
303802	Fedora 43 : firefox / nss (2026-d8099dd719)	Nessus	Fedora Local Security Checks	critical
303506	Mozilla Thunderbird < 149.0	Nessus	Windows	critical
303504	Mozilla Thunderbird < 149.0	Nessus	MacOS X Local Security Checks	critical
303474	Mozilla Firefox < 149.0	Nessus	Windows	critical
303471	Mozilla Firefox < 149.0	Nessus	MacOS X Local Security Checks	critical

Detections

Analytics

CVE-2026-4728

medium

Tenable Plugins

critical

critical

medium

critical

critical

critical

critical

critical

critical