The version of Firefox installed on the remote Windows host is prior to 158.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-106 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 Thunderbird installed on the remote macOS or Mac OS X host is prior to 158.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-109 advisory.

  - Mitigation bypass in the File Handling component. This vulnerability was fixed in Firefox 157.0.1.
    (CVE-2026-106016)

  - Several buffer-growth sites in libmime performed size arithmetic in 32-bit types without overflow checks.
    On a sufficiently large message the growth guard could fail open, or the buffer could be reallocated     smaller than required, and a subsequent memcpy would then write attacker-controlled data across adjacent     heap allocations. (CVE-2026-110247)

  - 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 Fedora 44 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-469a21a80e advisory.

    - Updated to latest upstream (158.0)

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 158.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-109 advisory.

  - Mitigation bypass in the File Handling component. This vulnerability was fixed in Firefox 157.0.1.
    (CVE-2026-106016)

  - Several buffer-growth sites in libmime performed size arithmetic in 32-bit types without overflow checks.
    On a sufficiently large message the growth guard could fail open, or the buffer could be reallocated     smaller than required, and a subsequent memcpy would then write attacker-controlled data across adjacent     heap allocations. (CVE-2026-110247)

  - 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 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 version of Firefox installed on the remote macOS or Mac OS X host is prior to 158.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-106 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
365314	Mozilla Firefox < 158.0	Nessus	Windows	10/13/2026	10/14/2026	critical
365312	Mozilla Firefox ESR < 153.5	Nessus	MacOS X Local Security Checks	10/13/2026	10/14/2026	critical
365352	Mozilla Thunderbird < 158.0	Nessus	MacOS X Local Security Checks	10/13/2026	10/13/2026	critical
365511	Fedora 44 : firefox (2026-469a21a80e)	Nessus	Fedora Local Security Checks	10/14/2026	10/14/2026	critical
365350	Mozilla Thunderbird < 158.0	Nessus	Windows	10/13/2026	10/13/2026	critical
365351	Mozilla Thunderbird < 153.5	Nessus	MacOS X Local Security Checks	10/13/2026	10/13/2026	critical
365311	Mozilla Firefox < 158.0	Nessus	MacOS X Local Security Checks	10/13/2026	10/14/2026	critical
365313	Mozilla Firefox ESR < 153.5	Nessus	Windows	10/13/2026	10/14/2026	critical
365349	Mozilla Thunderbird < 153.5	Nessus	Windows	10/13/2026	10/13/2026	critical
365635	Debian dsa-6560 : firefox-esr - security update	Nessus	Debian Local Security Checks	10/14/2026	10/14/2026	critical

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