Triggering an error condition in certain MIME bodies would cause uninitialized memory to be used. This vulnerability was fixed in Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.

The remote Fedora 44 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-379e77483b advisory.

    Update to latest stable upstream version.

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 45 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-aa0e0deed1 advisory.

    Update to latest stable upstream version.

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 Debian 12 host has packages installed that are affected by multiple vulnerabilities as referenced in the dla-4775 advisory.

    - -------------------------------------------------------------------------     Debian LTS Advisory DLA-4775-1                debian-lts@lists.debian.org     https://www.debian.org/lts/security/               Emilio Pozuelo Monfort     September 07, 2026                            https://wiki.debian.org/LTS
    - -------------------------------------------------------------------------

    Package        : thunderbird     Version        : 1:140.15.0esr-1~deb12u1     CVE ID         : CVE-2026-16365 CVE-2026-16371 CVE-2026-75874 CVE-2026-84119                      CVE-2026-84120 CVE-2026-84121 CVE-2026-84122 CVE-2026-84124                      CVE-2026-84131 CVE-2026-84143 CVE-2026-84145 CVE-2026-84639                      CVE-2026-84640 CVE-2026-84641

    Multiple security issues were discovered in Thunderbird, which could     result in the execution of arbitrary code or information disclosure.

    For Debian 12 bookworm, these problems have been fixed in version     1:140.15.0esr-1~deb12u1.

    We recommend that you upgrade your thunderbird packages.

    For the detailed security status of thunderbird please refer to     its security tracker page at:
    https://security-tracker.debian.org/tracker/thunderbird

    Further information about Debian LTS security advisories, how to apply     these updates to your system and frequently asked questions can be     found at: https://wiki.debian.org/LTS

Tenable has extracted the preceding description block directly from the Debian 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 140.15.0esr / 153.2.0esr. It is, therefore, affected by multiple vulnerabilities as referenced in the SSA:2026-247-03 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 remote Debian 13 host has packages installed that are affected by multiple vulnerabilities as referenced in the dsa-6483 advisory.

    - -------------------------------------------------------------------------     Debian Security Advisory DSA-6483-1                   security@debian.org     https://www.debian.org/security/                       Moritz Muehlenhoff     September 04, 2026                    https://www.debian.org/security/faq
    - -------------------------------------------------------------------------

    Package        : thunderbird     CVE ID         : CVE-2026-16365 CVE-2026-16371 CVE-2026-75874 CVE-2026-84119                      CVE-2026-84120 CVE-2026-84121 CVE-2026-84122 CVE-2026-84124                      CVE-2026-84131 CVE-2026-84143 CVE-2026-84145 CVE-2026-84639                      CVE-2026-84640 CVE-2026-84641

    Multiple security issues were discovered in Thunderbird, which could     result in the execution of arbitrary code or information disclosure.

    For the stable distribution (trixie), these problems have been fixed in     version 1:140.15.0esr-1~deb13u1.

    We recommend that you upgrade your thunderbird packages.

    For the detailed security status of thunderbird please refer to     its security tracker page at:
    https://security-tracker.debian.org/tracker/thunderbird

    Further information about Debian Security Advisories, how to apply     these updates to your system and frequently asked questions can be     found at: https://www.debian.org/security/

    Mailing list: debian-security-announce@lists.debian.org

Tenable has extracted the preceding description block directly from the Debian 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.

  - Triggering an error condition in certain MIME bodies would cause uninitialized memory to be used. This     vulnerability was fixed in Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2. (CVE-2026-84639)

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

The version of Thunderbird installed on the remote macOS or Mac OS X host is prior to 155.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-86 advisory.

  - Privilege escalation due to invalid pointer in the Graphics component. This vulnerability was fixed in     Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird     140.15, and Thunderbird 153.2. (CVE-2026-84131)

  - Sandbox escape due to use-after-free in the DOM: Security component. This vulnerability was fixed in     Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird     140.15, and Thunderbird 153.2. (CVE-2026-84121)

  - Triggering an error condition in certain MIME bodies would cause uninitialized memory to be used.
    (CVE-2026-84639)

  - A maliciously constructed mail header could lead to a one byte read past the end of a buffer.
    (CVE-2026-84640)

  - A malicious IMAP server can trigger use-after-free and heap-memory disclosure by sending a crafted ID     response. Heap contents can ultimately be persisted to prefs.js. (CVE-2026-84641)

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 153.2. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-88 advisory.

  - Privilege escalation due to invalid pointer in the Graphics component. This vulnerability was fixed in     Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird     140.15, and Thunderbird 153.2. (CVE-2026-84131)

  - Sandbox escape in the Remote Settings Client component. This vulnerability was fixed in Firefox 154,     Thunderbird 154, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 140.15, and     Thunderbird 153.2. (CVE-2026-75874)

  - Triggering an error condition in certain MIME bodies would cause uninitialized memory to be used.
    (CVE-2026-84639)

  - A maliciously constructed mail header could lead to a one byte read past the end of a buffer.
    (CVE-2026-84640)

  - A malicious IMAP server can trigger use-after-free and heap-memory disclosure by sending a crafted ID     response. Heap contents can ultimately be persisted to prefs.js. (CVE-2026-84641)

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 153.2. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-88 advisory.

  - Privilege escalation due to invalid pointer in the Graphics component. This vulnerability was fixed in     Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird     140.15, and Thunderbird 153.2. (CVE-2026-84131)

  - Sandbox escape in the Remote Settings Client component. This vulnerability was fixed in Firefox 154,     Thunderbird 154, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 140.15, and     Thunderbird 153.2. (CVE-2026-75874)

  - Triggering an error condition in certain MIME bodies would cause uninitialized memory to be used.
    (CVE-2026-84639)

  - A maliciously constructed mail header could lead to a one byte read past the end of a buffer.
    (CVE-2026-84640)

  - A malicious IMAP server can trigger use-after-free and heap-memory disclosure by sending a crafted ID     response. Heap contents can ultimately be persisted to prefs.js. (CVE-2026-84641)

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 140.15. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-87 advisory.

  - Privilege escalation due to invalid pointer in the Graphics component. This vulnerability was fixed in     Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird     140.15, and Thunderbird 153.2. (CVE-2026-84131)

  - Sandbox escape in the Remote Settings Client component. This vulnerability was fixed in Firefox 154,     Thunderbird 154, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 140.15, and     Thunderbird 153.2. (CVE-2026-75874)

  - Triggering an error condition in certain MIME bodies would cause uninitialized memory to be used.
    (CVE-2026-84639)

  - A maliciously constructed mail header could lead to a one byte read past the end of a buffer.
    (CVE-2026-84640)

  - A malicious IMAP server can trigger use-after-free and heap-memory disclosure by sending a crafted ID     response. Heap contents can ultimately be persisted to prefs.js. (CVE-2026-84641)

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 140.15. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-87 advisory.

  - Privilege escalation due to invalid pointer in the Graphics component. This vulnerability was fixed in     Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird     140.15, and Thunderbird 153.2. (CVE-2026-84131)

  - Sandbox escape in the Remote Settings Client component. This vulnerability was fixed in Firefox 154,     Thunderbird 154, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 140.15, and     Thunderbird 153.2. (CVE-2026-75874)

  - Triggering an error condition in certain MIME bodies would cause uninitialized memory to be used.
    (CVE-2026-84639)

  - A maliciously constructed mail header could lead to a one byte read past the end of a buffer.
    (CVE-2026-84640)

  - A malicious IMAP server can trigger use-after-free and heap-memory disclosure by sending a crafted ID     response. Heap contents can ultimately be persisted to prefs.js. (CVE-2026-84641)

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 155.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-86 advisory.

  - Privilege escalation due to invalid pointer in the Graphics component. This vulnerability was fixed in     Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird     140.15, and Thunderbird 153.2. (CVE-2026-84131)

  - Sandbox escape due to use-after-free in the DOM: Security component. This vulnerability was fixed in     Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird     140.15, and Thunderbird 153.2. (CVE-2026-84121)

  - Triggering an error condition in certain MIME bodies would cause uninitialized memory to be used.
    (CVE-2026-84639)

  - A maliciously constructed mail header could lead to a one byte read past the end of a buffer.
    (CVE-2026-84640)

  - A malicious IMAP server can trigger use-after-free and heap-memory disclosure by sending a crafted ID     response. Heap contents can ultimately be persisted to prefs.js. (CVE-2026-84641)

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
348353	Fedora 44 : thunderbird (2026-379e77483b)	Nessus	Fedora Local Security Checks	Local	critical
348331	Fedora 45 : thunderbird (2026-aa0e0deed1)	Nessus	Fedora Local Security Checks	Local	critical
348282	SUSE SLED15: MozillaThunderbird / MozillaThunderbird-translations-common / etc (SUSE-SU-2026:4268-1)	Nessus	SuSE Local Security Checks	Local	critical
343416	Debian dla-4775 : thunderbird - security update	Nessus	Debian Local Security Checks	Local	critical
343051	Slackware Linux 15.0 / current mozilla-thunderbird Multiple Vulnerabilities (SSA:2026-247-03)	Nessus	Slackware Local Security Checks	Local	critical
342858	Debian dsa-6483 : thunderbird - security update	Nessus	Debian Local Security Checks	Local	critical
342421	Linux Distros Unpatched Vulnerability : CVE-2026-84639	Nessus	Misc.	Local	critical
342261	Mozilla Thunderbird < 155.0	Nessus	MacOS X Local Security Checks	Local	critical
342260	Mozilla Thunderbird < 153.2	Nessus	MacOS X Local Security Checks	Local	critical
342259	Mozilla Thunderbird < 153.2	Nessus	Windows	Local	critical
342258	Mozilla Thunderbird < 140.15	Nessus	Windows	Local	critical
342257	Mozilla Thunderbird < 140.15	Nessus	MacOS X Local Security Checks	Local	critical
342256	Mozilla Thunderbird < 155.0	Nessus	Windows	Local	critical

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