Sandbox escape due to use-after-free in the Widget component. This vulnerability was fixed in Firefox 159, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.

The remote Debian 12 host has packages installed that are affected by multiple vulnerabilities as referenced in the dla-4866 advisory.

    - -------------------------------------------------------------------------     Debian LTS Advisory DLA-4866-1                debian-lts@lists.debian.org     https://www.debian.org/lts/security/               Emilio Pozuelo Monfort     October 29, 2026                              https://wiki.debian.org/LTS
    - -------------------------------------------------------------------------

    Package        : firefox-esr     Version        : 153.6.0esr-1~deb12u2     CVE ID         : CVE-2026-100801 CVE-2026-117860 CVE-2026-117861 CVE-2026-117862                      CVE-2026-117863 CVE-2026-117864 CVE-2026-117865 CVE-2026-117866                      CVE-2026-117867 CVE-2026-117868 CVE-2026-117869 CVE-2026-117870                      CVE-2026-117871 CVE-2026-117872 CVE-2026-117873 CVE-2026-117874                      CVE-2026-117875 CVE-2026-117876 CVE-2026-117877 CVE-2026-117878                      CVE-2026-117879 CVE-2026-117880 CVE-2026-117881 CVE-2026-117882                      CVE-2026-117883 CVE-2026-117884 CVE-2026-117885 CVE-2026-117886                      CVE-2026-117887 CVE-2026-117888 CVE-2026-117889 CVE-2026-117890                      CVE-2026-117891 CVE-2026-117892 CVE-2026-117893 CVE-2026-117894                      CVE-2026-117895 CVE-2026-117896 CVE-2026-117897 CVE-2026-117898                      CVE-2026-117899 CVE-2026-117900 CVE-2026-117901 CVE-2026-117902                      CVE-2026-117903 CVE-2026-117904 CVE-2026-117905 CVE-2026-117906                      CVE-2026-117907 CVE-2026-117908 CVE-2026-117909 CVE-2026-117910                      CVE-2026-117911 CVE-2026-117912 CVE-2026-117913 CVE-2026-117914                      CVE-2026-117915 CVE-2026-117916 CVE-2026-117917 CVE-2026-117918                      CVE-2026-117919 CVE-2026-117920 CVE-2026-117921 CVE-2026-117922                      CVE-2026-117923 CVE-2026-117924 CVE-2026-117925 CVE-2026-117926                      CVE-2026-117927 CVE-2026-117928 CVE-2026-117929 CVE-2026-117930                      CVE-2026-117931 CVE-2026-117932 CVE-2026-117933 CVE-2026-117934                      CVE-2026-117935 CVE-2026-117936 CVE-2026-117937 CVE-2026-117938                      CVE-2026-117939 CVE-2026-117940 CVE-2026-117941 CVE-2026-117942                      CVE-2026-117943 CVE-2026-117944 CVE-2026-117945 CVE-2026-117946                      CVE-2026-117947 CVE-2026-117948 CVE-2026-117949 CVE-2026-117950                      CVE-2026-117951 CVE-2026-117952 CVE-2026-117953 CVE-2026-117954                      CVE-2026-117955 CVE-2026-117956 CVE-2026-117957 CVE-2026-117958                      CVE-2026-117959 CVE-2026-117960 CVE-2026-117961 CVE-2026-117962                      CVE-2026-117963 CVE-2026-117964 CVE-2026-117965 CVE-2026-117966                      CVE-2026-117967 CVE-2026-117968 CVE-2026-117969 CVE-2026-117970                      CVE-2026-117971 CVE-2026-117972 CVE-2026-117973 CVE-2026-117974                      CVE-2026-117975 CVE-2026-117976 CVE-2026-117977 CVE-2026-117978                      CVE-2026-117979 CVE-2026-117980 CVE-2026-117981 CVE-2026-117982                      CVE-2026-117983 CVE-2026-117984 CVE-2026-117985 CVE-2026-117986                      CVE-2026-117987 CVE-2026-117988 CVE-2026-117989 CVE-2026-117990                      CVE-2026-117991 CVE-2026-117992 CVE-2026-117993 CVE-2026-117994                      CVE-2026-117995 CVE-2026-117996 CVE-2026-117997 CVE-2026-117998                      CVE-2026-117999 CVE-2026-118000 CVE-2026-118002 CVE-2026-118003                      CVE-2026-118004

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

    For Debian 12 bookworm, these problems have been fixed in version     153.6.0esr-1~deb12u2.

    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 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 Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - Sandbox escape due to use-after-free in the Widget component. This vulnerability was fixed in Firefox 159,     Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6. (CVE-2026-117997)

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 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.

ID	Name	Product	Family	Type	Severity
373648	Debian dla-4866 : firefox-esr - security update	Nessus	Debian Local Security Checks	Local	high
373488	Fedora 44 : firefox (2026-31601794bf)	Nessus	Fedora Local Security Checks	Local	high
372841	Linux Distros Unpatched Vulnerability : CVE-2026-117997	Nessus	Misc.	Local	critical
372632	Mozilla Thunderbird < 153.6	Nessus	Windows	Local	high
372631	Mozilla Firefox < 159.0	Nessus	MacOS X Local Security Checks	Local	high
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

Detections

Analytics

CVE-2026-117997

critical

Tenable Plugins

high

high

critical

high

high

high

high

high

high

high

high