Spoofing issue in Thunderbird. This vulnerability affects Thunderbird < 149 and Thunderbird < 140.9.

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

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 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 140.9. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-24 advisory.

  - Privilege escalation in the Netmonitor component. This vulnerability affects Firefox < 149, Firefox ESR <     140.9, Thunderbird < 149, and Thunderbird < 140.9. (CVE-2026-4717)

  - 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)

  - 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)

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 Thunderbird installed on the remote Windows host is prior to 140.9. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-24 advisory.

  - Privilege escalation in the Netmonitor component. This vulnerability affects Firefox < 149, Firefox ESR <     140.9, Thunderbird < 149, and Thunderbird < 140.9. (CVE-2026-4717)

  - 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)

  - 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)

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
303534	Linux Distros Unpatched Vulnerability : CVE-2026-3889	Nessus	Misc.	medium
303506	Mozilla Thunderbird < 149.0	Nessus	Windows	critical
303505	Mozilla Thunderbird < 140.9	Nessus	MacOS X Local Security Checks	critical
303504	Mozilla Thunderbird < 149.0	Nessus	MacOS X Local Security Checks	critical
303503	Mozilla Thunderbird < 140.9	Nessus	Windows	critical

Detections

Analytics

CVE-2026-3889

high

Tenable Plugins

medium

critical

critical

critical

critical