Use-after-free in the DOM: Events component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.

debian_linux dla-4866: Debian dla-4866 : firefox-esr - security update

fedora FEDORA-2026-31601794bf: firefox-159.0-1.fc44

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: Events component. This vulnerability was fixed in Firefox 159, Firefox ESR     115.44, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6. (CVE-2026-117931)

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

The version of Thunderbird installed on the remote Windows host is prior to 153.6. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-122 advisory.

  - Privilege escalation in the DLL Services component. This vulnerability was fixed in Firefox ESR 153.4,     Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 159, Firefox ESR 153.6, Thunderbird 159,     Thunderbird 153.6, Firefox 157, and Firefox ESR 140.17. (CVE-2026-100801)

  - 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 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 Firefox ESR installed on the remote Windows host is prior to 115.44. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-119 advisory.

  - Sandbox escape due to incorrect boundary conditions in the Networking component. This vulnerability was     fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, Thunderbird 153.5, and Firefox ESR 115.44.
    (CVE-2026-109708)

  - Sandbox escape, site isolation issue due to incorrect boundary conditions, use-after-free in the     Networking component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158,     Thunderbird 153.5, and Firefox ESR 115.44. (CVE-2026-109705)

  - 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)

  - Privilege escalation due to use-after-free in the Graphics: Canvas2D component. This vulnerability was     fixed in Firefox 159, Firefox ESR 115.44, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
    (CVE-2026-117866)

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 153.6. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-120 advisory.

  - Privilege escalation in the DLL Services component. This vulnerability was fixed in Firefox ESR 153.4,     Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 159, Firefox ESR 153.6, Thunderbird 159,     Thunderbird 153.6, Firefox 157, and Firefox ESR 140.17. (CVE-2026-100801)

  - 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 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 Firefox ESR installed on the remote Windows host is prior to 153.6. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-120 advisory.

  - Privilege escalation in the DLL Services component. This vulnerability was fixed in Firefox ESR 153.4,     Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 159, Firefox ESR 153.6, Thunderbird 159,     Thunderbird 153.6, Firefox 157, and Firefox ESR 140.17. (CVE-2026-100801)

  - 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 version of Thunderbird installed on the remote macOS or Mac OS X host is prior to 153.6. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-122 advisory.

  - Privilege escalation in the DLL Services component. This vulnerability was fixed in Firefox ESR 153.4,     Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 159, Firefox ESR 153.6, Thunderbird 159,     Thunderbird 153.6, Firefox 157, and Firefox ESR 140.17. (CVE-2026-100801)

  - 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 version of Firefox ESR installed on the remote macOS or Mac OS X host is prior to 115.44. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2026-119 advisory.

  - Sandbox escape due to incorrect boundary conditions in the Networking component. This vulnerability was     fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, Thunderbird 153.5, and Firefox ESR 115.44.
    (CVE-2026-109708)

  - Sandbox escape, site isolation issue due to incorrect boundary conditions, use-after-free in the     Networking component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158,     Thunderbird 153.5, and Firefox ESR 115.44. (CVE-2026-109705)

  - 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)

  - Privilege escalation due to use-after-free in the Graphics: Canvas2D component. This vulnerability was     fixed in Firefox 159, Firefox ESR 115.44, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
    (CVE-2026-117866)

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
372750	Linux Distros Unpatched Vulnerability : CVE-2026-117931	Nessus	Misc.	Local	high
372632	Mozilla Thunderbird < 153.6	Nessus	Windows	Local	high
372631	Mozilla Firefox < 159.0	Nessus	MacOS X Local Security Checks	Local	high
372630	Mozilla Firefox ESR < 115.44	Nessus	Windows	Local	critical
372629	Mozilla Firefox ESR < 153.6	Nessus	MacOS X Local Security Checks	Local	high
372628	Mozilla Thunderbird < 159.0	Nessus	Windows	Local	high
372627	Mozilla Firefox < 159.0	Nessus	Windows	Local	high
372626	Mozilla Firefox ESR < 153.6	Nessus	Windows	Local	high
372625	Mozilla Thunderbird < 159.0	Nessus	MacOS X Local Security Checks	Local	high
372624	Mozilla Thunderbird < 153.6	Nessus	MacOS X Local Security Checks	Local	high
372623	Mozilla Firefox ESR < 115.44	Nessus	MacOS X Local Security Checks	Local	critical

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