A maliciously constructed mail header could lead to multiple fields being parsed as one, or potential memory safety violations. This vulnerability was fixed in Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.3.

mozilla mfsa2026-96: Security Vulnerabilities fixed in Thunderbird 153.3

The version of Thunderbird installed on the remote Windows host is prior to 156.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-94 advisory.

  - Privilege escalation in the Enterprise Policies component. This vulnerability was fixed in Firefox 156,     Firefox ESR 153.3, and Thunderbird 156. (CVE-2026-92073)

  - A maliciously constructed mail header could lead to multiple fields being parsed as one, or potential     memory safety violations. (CVE-2026-92238)

  - A maliciously constructed IMAP line could cause an out-of-bounds buffer read. (CVE-2026-92239)

  - A malicious or compromised IMAP server can trigger an out-of-bounds read in the IMAP response parser by     sending an untagged ' ID' response, crashing Thunderbird. The affected parsing path is reachable before     authentication. (CVE-2026-92240)

  - Use-after-free in the Audio/Video: Web Codecs component. This vulnerability was fixed in Firefox 156,     Firefox ESR 140.16, Firefox ESR 153.3, Thunderbird 156, and Thunderbird 140.16. (CVE-2026-92005)

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 140.16. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-95 advisory.

  - Privilege escalation due to incorrect boundary conditions in the Graphics: WebRender component. This     vulnerability was fixed in Firefox 156, Firefox ESR 115.41, Firefox ESR 140.16, Firefox ESR 153.3,     Thunderbird 156, and Thunderbird 140.16. (CVE-2026-92020)

  - A maliciously constructed mail header could lead to multiple fields being parsed as one, or potential     memory safety violations. (CVE-2026-92238)

  - A maliciously constructed IMAP line could cause an out-of-bounds buffer read. (CVE-2026-92239)

  - A malicious or compromised IMAP server can trigger an out-of-bounds read in the IMAP response parser by     sending an untagged ' ID' response, crashing Thunderbird. The affected parsing path is reachable before     authentication. (CVE-2026-92240)

  - Use-after-free in the Audio/Video: Web Codecs component. This vulnerability was fixed in Firefox 156,     Firefox ESR 140.16, Firefox ESR 153.3, Thunderbird 156, and Thunderbird 140.16. (CVE-2026-92005)

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 140.16. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-95 advisory.

  - Privilege escalation due to incorrect boundary conditions in the Graphics: WebRender component. This     vulnerability was fixed in Firefox 156, Firefox ESR 115.41, Firefox ESR 140.16, Firefox ESR 153.3,     Thunderbird 156, and Thunderbird 140.16. (CVE-2026-92020)

  - A maliciously constructed mail header could lead to multiple fields being parsed as one, or potential     memory safety violations. (CVE-2026-92238)

  - A maliciously constructed IMAP line could cause an out-of-bounds buffer read. (CVE-2026-92239)

  - A malicious or compromised IMAP server can trigger an out-of-bounds read in the IMAP response parser by     sending an untagged ' ID' response, crashing Thunderbird. The affected parsing path is reachable before     authentication. (CVE-2026-92240)

  - Use-after-free in the Audio/Video: Web Codecs component. This vulnerability was fixed in Firefox 156,     Firefox ESR 140.16, Firefox ESR 153.3, Thunderbird 156, and Thunderbird 140.16. (CVE-2026-92005)

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 156.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-94 advisory.

  - Privilege escalation in the Enterprise Policies component. This vulnerability was fixed in Firefox 156,     Firefox ESR 153.3, and Thunderbird 156. (CVE-2026-92073)

  - A maliciously constructed mail header could lead to multiple fields being parsed as one, or potential     memory safety violations. (CVE-2026-92238)

  - A maliciously constructed IMAP line could cause an out-of-bounds buffer read. (CVE-2026-92239)

  - A malicious or compromised IMAP server can trigger an out-of-bounds read in the IMAP response parser by     sending an untagged ' ID' response, crashing Thunderbird. The affected parsing path is reachable before     authentication. (CVE-2026-92240)

  - Use-after-free in the Audio/Video: Web Codecs component. This vulnerability was fixed in Firefox 156,     Firefox ESR 140.16, Firefox ESR 153.3, Thunderbird 156, and Thunderbird 140.16. (CVE-2026-92005)

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
346179	Mozilla Thunderbird < 156.0	Nessus	Windows	Local	high
346178	Mozilla Thunderbird < 140.16	Nessus	MacOS X Local Security Checks	Local	high
346177	Mozilla Thunderbird < 140.16	Nessus	Windows	Local	high
346176	Mozilla Thunderbird < 156.0	Nessus	MacOS X Local Security Checks	Local	high

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