The version of Thunderbird installed on the remote macOS or Mac OS X host is prior to 153.5. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-110 advisory.

  - Privilege escalation in the WebExtensions component. This vulnerability was fixed in Firefox 158 and     Firefox ESR 153.5. (CVE-2026-109778)

  - Sandbox escape due to use-after-free in the Networking component. This vulnerability was fixed in Firefox     158 and Firefox ESR 153.5. (CVE-2026-109707)

  - A malicious, compromised, or MITM-controlled Exchange server can return a single well-formed SOAP response     containing an element with enough attributes to keep Thunderbird's main thread CPU-bound for seconds to     hours. (CVE-2026-110249)

  - Privilege escalation in the Application Update component. This vulnerability was fixed in Firefox 158 and     Firefox ESR 153.5. (CVE-2026-109704)

  - Sandbox escape, site isolation issue due to incorrect boundary conditions, use-after-free in the     Networking component. This vulnerability was fixed in Firefox 158 and Firefox ESR 153.5. (CVE-2026-109705)

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-4836 advisory.

    - -------------------------------------------------------------------------     Debian LTS Advisory DLA-4836-1                debian-lts@lists.debian.org     https://www.debian.org/lts/security/               Emilio Pozuelo Monfort     October 15, 2026                              https://wiki.debian.org/LTS
    - -------------------------------------------------------------------------

    Package        : firefox-esr     Version        : 153.5.0esr-1~deb12u1     CVE ID         : CVE-2026-109705 CVE-2026-109706 CVE-2026-109707 CVE-2026-109708                      CVE-2026-109709 CVE-2026-109710 CVE-2026-109711 CVE-2026-109712                      CVE-2026-109713 CVE-2026-109715 CVE-2026-109716 CVE-2026-109717                      CVE-2026-109718 CVE-2026-109719 CVE-2026-109720 CVE-2026-109721                      CVE-2026-109722 CVE-2026-109723 CVE-2026-109724 CVE-2026-109725                      CVE-2026-109726 CVE-2026-109727 CVE-2026-109728 CVE-2026-109729                      CVE-2026-109730 CVE-2026-109731 CVE-2026-109732 CVE-2026-109733                      CVE-2026-109734 CVE-2026-109736 CVE-2026-109737 CVE-2026-109738                      CVE-2026-109741 CVE-2026-109742 CVE-2026-109743 CVE-2026-109744                      CVE-2026-109745 CVE-2026-109751 CVE-2026-109752 CVE-2026-109753                      CVE-2026-109754 CVE-2026-109756 CVE-2026-109757 CVE-2026-109759                      CVE-2026-109760 CVE-2026-109762 CVE-2026-109763 CVE-2026-109764                      CVE-2026-109765 CVE-2026-109766 CVE-2026-109767 CVE-2026-109770                      CVE-2026-109775 CVE-2026-109776 CVE-2026-109777 CVE-2026-109778                      CVE-2026-109781 CVE-2026-109782 CVE-2026-109783

    Multiple security issues have been found in the Mozilla Firefox web     browser, which could potentially result in the execution of arbitrary     code, sandbox escape, information disclosure, mitigation bypass or     privilege escalation.

    For Debian 12 bookworm, these problems have been fixed in version     153.5.0esr-1~deb12u1.

    We recommend that you upgrade your firefox-esr packages.

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

    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 Firefox ESR installed on the remote macOS or Mac OS X host is prior to 153.5. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-108 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 Firefox ESR installed on the remote Windows host is prior to 153.5. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-108 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 153.5. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-110 advisory.

  - Privilege escalation in the WebExtensions component. This vulnerability was fixed in Firefox 158 and     Firefox ESR 153.5. (CVE-2026-109778)

  - Sandbox escape due to use-after-free in the Networking component. This vulnerability was fixed in Firefox     158 and Firefox ESR 153.5. (CVE-2026-109707)

  - A malicious, compromised, or MITM-controlled Exchange server can return a single well-formed SOAP response     containing an element with enough attributes to keep Thunderbird's main thread CPU-bound for seconds to     hours. (CVE-2026-110249)

  - Privilege escalation in the Application Update component. This vulnerability was fixed in Firefox 158 and     Firefox ESR 153.5. (CVE-2026-109704)

  - Sandbox escape, site isolation issue due to incorrect boundary conditions, use-after-free in the     Networking component. This vulnerability was fixed in Firefox 158 and Firefox ESR 153.5. (CVE-2026-109705)

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-6560 advisory.

    - -------------------------------------------------------------------------     Debian Security Advisory DSA-6560-1                   security@debian.org     https://www.debian.org/security/                       Moritz Muehlenhoff     October 14, 2026                      https://www.debian.org/security/faq
    - -------------------------------------------------------------------------

    Package        : firefox-esr     CVE ID         : CVE-2026-109705 CVE-2026-109706 CVE-2026-109707 CVE-2026-109708                      CVE-2026-109709 CVE-2026-109710 CVE-2026-109711 CVE-2026-109712                      CVE-2026-109713 CVE-2026-109715 CVE-2026-109716 CVE-2026-109717                      CVE-2026-109718 CVE-2026-109719 CVE-2026-109720 CVE-2026-109721                      CVE-2026-109722 CVE-2026-109723 CVE-2026-109724 CVE-2026-109725                      CVE-2026-109726 CVE-2026-109727 CVE-2026-109728 CVE-2026-109729                      CVE-2026-109730 CVE-2026-109731 CVE-2026-109732 CVE-2026-109733                      CVE-2026-109734 CVE-2026-109736 CVE-2026-109737 CVE-2026-109738                      CVE-2026-109741 CVE-2026-109742 CVE-2026-109743 CVE-2026-109744                      CVE-2026-109745 CVE-2026-109751 CVE-2026-109752 CVE-2026-109753                      CVE-2026-109754 CVE-2026-109756 CVE-2026-109757 CVE-2026-109759                      CVE-2026-109760 CVE-2026-109762 CVE-2026-109763 CVE-2026-109764                      CVE-2026-109765 CVE-2026-109766 CVE-2026-109767 CVE-2026-109770                      CVE-2026-109775 CVE-2026-109776 CVE-2026-109777 CVE-2026-109778                      CVE-2026-109781 CVE-2026-109782 CVE-2026-109783

    Multiple security issues have been found in the Mozilla Firefox web     browser, which could potentially result in the execution of arbitrary     code, sandbox escape, information disclosure, mitigation bypass or     privilege escalation.

    For the stable distribution (trixie), these problems have been fixed in     version 153.5.0esr-1~deb13u1.

    We recommend that you upgrade your firefox-esr packages.

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

    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.

ID	Name	Product	Family	Published	Updated	Severity
365351	Mozilla Thunderbird < 153.5	Nessus	MacOS X Local Security Checks	10/13/2026	10/16/2026	critical
366095	Debian dla-4836 : firefox-esr - security update	Nessus	Debian Local Security Checks	10/15/2026	10/16/2026	critical
365312	Mozilla Firefox ESR < 153.5	Nessus	MacOS X Local Security Checks	10/13/2026	10/16/2026	critical
365313	Mozilla Firefox ESR < 153.5	Nessus	Windows	10/13/2026	10/16/2026	critical
365349	Mozilla Thunderbird < 153.5	Nessus	Windows	10/13/2026	10/16/2026	critical
365635	Debian dsa-6560 : firefox-esr - security update	Nessus	Debian Local Security Checks	10/14/2026	10/16/2026	critical

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