RHSA-2026:73971 - Security Advisory

Topic

An update for thunderbird is now available for Red Hat Enterprise Linux 8.

Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.

Description

Mozilla Thunderbird is a standalone mail and newsgroup client.

Security Fix(es):

• firefox: thunderbird: Privilege escalation in the DOM: Workers component (CVE-2026-16365)
• firefox: thunderbird: Sandbox escape in the Remote Settings Client component (CVE-2026-75874)
• firefox: Sandbox escape due to use-after-free in the DOM: Security component (CVE-2026-84121)
• firefox: Internally found bugs fixed in Firefox 155, Firefox ESR 153.2, Firefox ESR 140.15 and Firefox ESR 115.40 (CVE-2026-84145)
• firefox: Sandbox escape due to use-after-free in the DOM: Navigation component (CVE-2026-84119)
• firefox: Use-after-free in the Audio/Video component (CVE-2026-84120)
• firefox: Privilege escalation due to invalid pointer in the Graphics component (CVE-2026-84131)
• firefox: Use-after-free in the DOM: Core & HTML component (CVE-2026-84124)
• firefox: Use-after-free in the Audio/Video component (CVE-2026-84122)
• firefox: Internally found bugs fixed in Firefox 155, Firefox ESR 153.2 and Firefox ESR 140.15 (CVE-2026-84143)
• thunderbird: Uninitialized memory in MIME parsing (CVE-2026-84639)
• thunderbird: Information disclosure due to malicious IMAP server response (CVE-2026-84641)
• thunderbird: One byte overflow read in mail parser (CVE-2026-84640)
• firefox: thunderbird: Use-after-free in the SVG component (CVE-2026-92024)
• firefox: thunderbird: Mitigation bypass in the Remote Settings Client component (CVE-2026-92019)
• firefox: thunderbird: Use-after-free in the Networking component (CVE-2026-92026)
• firefox: thunderbird: Information disclosure in the Graphics: ImageLib component (CVE-2026-92031)
• firefox: thunderbird: Sandbox escape due to invalid pointer in the Graphics component (CVE-2026-92032)
• firefox: thunderbird: Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component (CVE-2026-92010)
• firefox: thunderbird: Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component (CVE-2026-92006)
• firefox: thunderbird: Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component (CVE-2026-92011)
• firefox: thunderbird: Use-after-free in the DOM: Streams component (CVE-2026-92027)
• firefox: thunderbird: Use-after-free in the DOM: Core & HTML component (CVE-2026-92028)
• firefox: thunderbird: Privilege escalation in the WebExtensions component (CVE-2026-92015)
• firefox: thunderbird: Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component (CVE-2026-92013)
• firefox: thunderbird: Use-after-free in the Disability Access APIs component (CVE-2026-92016)
• firefox: thunderbird: Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component (CVE-2026-92012)
• firefox: thunderbird: Use-after-free in the DOM: HTML Parser component (CVE-2026-92022)
• firefox: thunderbird: Privilege escalation due to incorrect boundary conditions in the Graphics component (CVE-2026-92014)
• firefox: thunderbird: Sandbox escape in the DOM: Core & HTML component (CVE-2026-92018)
• firefox: thunderbird: Use-after-free in the JavaScript Engine: JIT component (CVE-2026-92021)
• firefox: thunderbird: Use-after-free in the Audio/Video: Web Codecs component (CVE-2026-92005)
• firefox: thunderbird: Privilege escalation in the DOM: Service Workers component (CVE-2026-92017)
• firefox: thunderbird: Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component (CVE-2026-92009)
• firefox: thunderbird: Privilege escalation due to incorrect boundary conditions in the Graphics: WebRender component (CVE-2026-92020)
• firefox: thunderbird: Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component (CVE-2026-92008)
• firefox: thunderbird: Mitigation bypass in the DOM: Copy & Paste and Drag & Drop component (CVE-2026-92030)
• firefox: thunderbird: Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component (CVE-2026-92007)
• firefox: thunderbird: Use-after-free in the DOM: Navigation component (CVE-2026-92025)
• firefox: thunderbird: Use-after-free in the SVG component (CVE-2026-92029)
• firefox: thunderbird: Use-after-free in the XML component (CVE-2026-92023)
• thunderbird: Out-of-bounds read in IMAP response parser (CVE-2026-92240)
• thunderbird: Thunderbird: Out-of-bounds read via maliciously constructed IMAP line (CVE-2026-92239)
• thunderbird: Thunderbird: Memory safety violations via maliciously crafted mail headers (CVE-2026-92238)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Solution

For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

Affected Products

• Red Hat Enterprise Linux for x86_64 8 x86_64
• Red Hat Enterprise Linux for IBM z Systems 8 s390x
• Red Hat Enterprise Linux for Power, little endian 8 ppc64le
• Red Hat Enterprise Linux for ARM 64 8 aarch64
• Red Hat Enterprise Linux for x86_64 - Extended Life Cycle 8.10 x86_64
• Red Hat Enterprise Linux for ARM 64 - Extended Life Cycle 8.10 aarch64
• Red Hat Enterprise Linux for Power, little endian - Extended Life Cycle 8.10 ppc64le
• Red Hat Enterprise Linux for IBM z Systems - Extended Life Cycle 8.10 s390x

Fixes

• BZ - 2503504 - CVE-2026-16365 firefox: thunderbird: Privilege escalation in the DOM: Workers component
• BZ - 2517832 - CVE-2026-75874 firefox: thunderbird: Sandbox escape in the Remote Settings Client component
• BZ - 2526753 - CVE-2026-84121 firefox: Sandbox escape due to use-after-free in the DOM: Security component
• BZ - 2526760 - CVE-2026-84145 firefox: Internally found bugs fixed in Firefox 155, Firefox ESR 153.2, Firefox ESR 140.15 and Firefox ESR 115.40
• BZ - 2526764 - CVE-2026-84119 firefox: Sandbox escape due to use-after-free in the DOM: Navigation component
• BZ - 2526765 - CVE-2026-84120 firefox: Use-after-free in the Audio/Video component
• BZ - 2526767 - CVE-2026-84131 firefox: Privilege escalation due to invalid pointer in the Graphics component
• BZ - 2526773 - CVE-2026-84124 firefox: Use-after-free in the DOM: Core & HTML component
• BZ - 2526778 - CVE-2026-84122 firefox: Use-after-free in the Audio/Video component
• BZ - 2526781 - CVE-2026-84143 firefox: Internally found bugs fixed in Firefox 155, Firefox ESR 153.2 and Firefox ESR 140.15
• BZ - 2527113 - CVE-2026-84639 thunderbird: Uninitialized memory in MIME parsing
• BZ - 2527115 - CVE-2026-84641 thunderbird: Information disclosure due to malicious IMAP server response
• BZ - 2527116 - CVE-2026-84640 thunderbird: One byte overflow read in mail parser
• BZ - 2533737 - CVE-2026-92024 firefox: thunderbird: Use-after-free in the SVG component
• BZ - 2533740 - CVE-2026-92019 firefox: thunderbird: Mitigation bypass in the Remote Settings Client component
• BZ - 2533741 - CVE-2026-92026 firefox: thunderbird: Use-after-free in the Networking component
• BZ - 2533742 - CVE-2026-92031 firefox: thunderbird: Information disclosure in the Graphics: ImageLib component
• BZ - 2533743 - CVE-2026-92032 firefox: thunderbird: Sandbox escape due to invalid pointer in the Graphics component
• BZ - 2533747 - CVE-2026-92010 firefox: thunderbird: Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component
• BZ - 2533751 - CVE-2026-92006 firefox: thunderbird: Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component
• BZ - 2533753 - CVE-2026-92011 firefox: thunderbird: Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component
• BZ - 2533757 - CVE-2026-92027 firefox: thunderbird: Use-after-free in the DOM: Streams component
• BZ - 2533758 - CVE-2026-92028 firefox: thunderbird: Use-after-free in the DOM: Core & HTML component
• BZ - 2533760 - CVE-2026-92015 firefox: thunderbird: Privilege escalation in the WebExtensions component
• BZ - 2533762 - CVE-2026-92013 firefox: thunderbird: Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component
• BZ - 2533764 - CVE-2026-92016 firefox: thunderbird: Use-after-free in the Disability Access APIs component
• BZ - 2533769 - CVE-2026-92012 firefox: thunderbird: Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component
• BZ - 2533770 - CVE-2026-92022 firefox: thunderbird: Use-after-free in the DOM: HTML Parser component
• BZ - 2533771 - CVE-2026-92014 firefox: thunderbird: Privilege escalation due to incorrect boundary conditions in the Graphics component
• BZ - 2533773 - CVE-2026-92018 firefox: thunderbird: Sandbox escape in the DOM: Core & HTML component
• BZ - 2533774 - CVE-2026-92021 firefox: thunderbird: Use-after-free in the JavaScript Engine: JIT component
• BZ - 2533778 - CVE-2026-92005 firefox: thunderbird: Use-after-free in the Audio/Video: Web Codecs component
• BZ - 2533779 - CVE-2026-92017 firefox: thunderbird: Privilege escalation in the DOM: Service Workers component
• BZ - 2533781 - CVE-2026-92009 firefox: thunderbird: Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component
• BZ - 2533786 - CVE-2026-92020 firefox: thunderbird: Privilege escalation due to incorrect boundary conditions in the Graphics: WebRender component
• BZ - 2533790 - CVE-2026-92008 firefox: thunderbird: Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component
• BZ - 2533791 - CVE-2026-92030 firefox: thunderbird: Mitigation bypass in the DOM: Copy & Paste and Drag & Drop component
• BZ - 2533792 - CVE-2026-92007 firefox: thunderbird: Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component
• BZ - 2533793 - CVE-2026-92025 firefox: thunderbird: Use-after-free in the DOM: Navigation component
• BZ - 2533797 - CVE-2026-92029 firefox: thunderbird: Use-after-free in the SVG component
• BZ - 2533799 - CVE-2026-92023 firefox: thunderbird: Use-after-free in the XML component
• BZ - 2534187 - CVE-2026-92240 thunderbird: Out-of-bounds read in IMAP response parser
• BZ - 2534197 - CVE-2026-92239 thunderbird: Thunderbird: Out-of-bounds read via maliciously constructed IMAP line
• BZ - 2534199 - CVE-2026-92238 thunderbird: Thunderbird: Memory safety violations via maliciously crafted mail headers

CVEs

• CVE-2026-16365
• CVE-2026-75874
• CVE-2026-84119
• CVE-2026-84120
• CVE-2026-84121
• CVE-2026-84122
• CVE-2026-84124
• CVE-2026-84131
• CVE-2026-84143
• CVE-2026-84145
• CVE-2026-84639
• CVE-2026-84640
• CVE-2026-84641
• CVE-2026-92005
• CVE-2026-92006
• CVE-2026-92007
• CVE-2026-92008
• CVE-2026-92009
• CVE-2026-92010
• CVE-2026-92011
• CVE-2026-92012
• CVE-2026-92013
• CVE-2026-92014
• CVE-2026-92015
• CVE-2026-92016
• CVE-2026-92017
• CVE-2026-92018
• CVE-2026-92019
• CVE-2026-92020
• CVE-2026-92021
• CVE-2026-92022
• CVE-2026-92023
• CVE-2026-92024
• CVE-2026-92025
• CVE-2026-92026
• CVE-2026-92027
• CVE-2026-92028
• CVE-2026-92029
• CVE-2026-92030
• CVE-2026-92031
• CVE-2026-92032
• CVE-2026-92238
• CVE-2026-92239
• CVE-2026-92240

References

• https://access.redhat.com/security/updates/classification/#important