The version of Firefox installed on the remote Windows host is prior to 159.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-118 advisory.

  - Privilege escalation in the DOM: Navigation component. This vulnerability was fixed in Firefox 159.
    (CVE-2026-118008)

  - Same-origin policy bypass in the DOM: Navigation component. This vulnerability was fixed in Firefox 159,     Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6. (CVE-2026-117860)

  - Sandbox escape in the DOM: Navigation component. This vulnerability was fixed in Firefox 159, Firefox ESR     153.6, Thunderbird 159, and Thunderbird 153.6. (CVE-2026-117861)

  - Privilege escalation due to incorrect boundary conditions in the Networking component. This vulnerability     was fixed in Firefox 159, Firefox ESR 115.44, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
    (CVE-2026-117862)

  - Information disclosure due to uninitialized memory in the Audio/Video component. This vulnerability was     fixed in Firefox 159, Firefox ESR 115.44, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
    (CVE-2026-117863)

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 159.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-121 advisory.

  - Privilege escalation in the DOM: Navigation component. This vulnerability was fixed in Firefox 159.
    (CVE-2026-118008)

  - When a message containing an OpenPGP key attachment was displayed, Thunderbird automatically loaded the     attachment's content to offer importing the key. A sender could mark the attachment as an external     attachment pointing to an arbitrary URL, which Thunderbird then loaded without any user interaction,     bypassing remote content blocking. On Windows, a URL pointing to an attacker-controlled network share     could leak the user's NTLM credentials.  The NTLM credential leak only affects Thunderbird on Windows. On     other operating systems, the issue allowed a remote request that bypassed remote content blocking.
    (CVE-2026-118174)

  - When replying to, forwarding, or editing a crafted email message as new, Thunderbird could embed parts of     a different message stored in the same folder into the message being composed, without showing a blocked     content warning. If the user sent the message, the content of the other message was disclosed to the     recipients. (CVE-2026-118175)

  - Thunderbird's check that prevents mailbox: URLs from accessing files on remote Windows network shares     could be bypassed using extended-length UNC paths. Displaying a specially crafted email could cause     Thunderbird to connect to an SMB server chosen by the attacker, disclosing the user's Windows account name     and NTLM authentication data, which could be used for offline password cracking or relay attacks.  This     bug only affects Thunderbird on Windows. Other operating systems are unaffected. (CVE-2026-118176)

  - When looking for calendars in a directory on a server, during account setup or when adding a new network     calendar, Thunderbird accepted calendar locations pointing to other servers, local files or network     shares. A malicious server, or a network attacker when the lookup used plain HTTP, could make Thunderbird     subscribe to such a location. On Windows this could leak the user's NTLM credentials to an attacker-     controlled host on every calendar refresh, and changes to the calendar could be written to the attacker's     share or overwrite a local file. (CVE-2026-118177)

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-2026-31601794bf advisory.

    - Updated to latest upstream (159.0)

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 Firefox installed on the remote macOS or Mac OS X host is prior to 159.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-118 advisory.

  - Privilege escalation in the DOM: Navigation component. This vulnerability was fixed in Firefox 159.
    (CVE-2026-118008)

  - Same-origin policy bypass in the DOM: Navigation component. This vulnerability was fixed in Firefox 159,     Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6. (CVE-2026-117860)

  - Sandbox escape in the DOM: Navigation component. This vulnerability was fixed in Firefox 159, Firefox ESR     153.6, Thunderbird 159, and Thunderbird 153.6. (CVE-2026-117861)

  - Privilege escalation due to incorrect boundary conditions in the Networking component. This vulnerability     was fixed in Firefox 159, Firefox ESR 115.44, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
    (CVE-2026-117862)

  - Information disclosure due to uninitialized memory in the Audio/Video component. This vulnerability was     fixed in Firefox 159, Firefox ESR 115.44, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
    (CVE-2026-117863)

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 159.0. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-121 advisory.

  - Privilege escalation in the DOM: Navigation component. This vulnerability was fixed in Firefox 159.
    (CVE-2026-118008)

  - When a message containing an OpenPGP key attachment was displayed, Thunderbird automatically loaded the     attachment's content to offer importing the key. A sender could mark the attachment as an external     attachment pointing to an arbitrary URL, which Thunderbird then loaded without any user interaction,     bypassing remote content blocking. On Windows, a URL pointing to an attacker-controlled network share     could leak the user's NTLM credentials.  The NTLM credential leak only affects Thunderbird on Windows. On     other operating systems, the issue allowed a remote request that bypassed remote content blocking.
    (CVE-2026-118174)

  - When replying to, forwarding, or editing a crafted email message as new, Thunderbird could embed parts of     a different message stored in the same folder into the message being composed, without showing a blocked     content warning. If the user sent the message, the content of the other message was disclosed to the     recipients. (CVE-2026-118175)

  - Thunderbird's check that prevents mailbox: URLs from accessing files on remote Windows network shares     could be bypassed using extended-length UNC paths. Displaying a specially crafted email could cause     Thunderbird to connect to an SMB server chosen by the attacker, disclosing the user's Windows account name     and NTLM authentication data, which could be used for offline password cracking or relay attacks.  This     bug only affects Thunderbird on Windows. Other operating systems are unaffected. (CVE-2026-118176)

  - When looking for calendars in a directory on a server, during account setup or when adding a new network     calendar, Thunderbird accepted calendar locations pointing to other servers, local files or network     shares. A malicious server, or a network attacker when the lookup used plain HTTP, could make Thunderbird     subscribe to such a location. On Windows this could leak the user's NTLM credentials to an attacker-     controlled host on every calendar refresh, and changes to the calendar could be written to the attacker's     share or overwrite a local file. (CVE-2026-118177)

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.

  - Use-after-free in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 159 and     Thunderbird 159. (CVE-2026-118016)

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

ID	Name	Product	Family	Published	Updated	Severity
372627	Mozilla Firefox < 159.0	Nessus	Windows	10/27/2026	10/27/2026	high
372625	Mozilla Thunderbird < 159.0	Nessus	MacOS X Local Security Checks	10/27/2026	10/27/2026	high
373488	Fedora 44 : firefox (2026-31601794bf)	Nessus	Fedora Local Security Checks	10/29/2026	10/29/2026	high
372631	Mozilla Firefox < 159.0	Nessus	MacOS X Local Security Checks	10/27/2026	10/27/2026	high
372628	Mozilla Thunderbird < 159.0	Nessus	Windows	10/27/2026	10/27/2026	high
373413	Linux Distros Unpatched Vulnerability : CVE-2026-118016	Nessus	Misc.	10/28/2026	10/28/2026	high

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