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OpenAdvisories
Critical RHSA-2026:81913 44 CVEs

Red Hat Security Advisory: thunderbird security update

Published Oct 14, 2026 · Updated Oct 16, 2026

Ecosystem: Red Hat

Fixed packages 6

ReleasePackageFixed in
Red Hat · RHEL 8.6 AUS rhel_aus:8.6::appstream thunderbird 0:140.16.0-1.el8_6
Red Hat · RHEL 8.6 AUS rhel_aus:8.6::appstream thunderbird-debuginfo 0:140.16.0-1.el8_6
Red Hat · RHEL 8.6 AUS rhel_aus:8.6::appstream thunderbird-debugsource 0:140.16.0-1.el8_6
Red Hat · RHEL 8.6 EUS Long Life rhel_eus_long_life:8.6::appstream thunderbird 0:140.16.0-1.el8_6
Red Hat · RHEL 8.6 EUS Long Life rhel_eus_long_life:8.6::appstream thunderbird-debuginfo 0:140.16.0-1.el8_6
Red Hat · RHEL 8.6 EUS Long Life rhel_eus_long_life:8.6::appstream thunderbird-debugsource 0:140.16.0-1.el8_6

Vulnerabilities 44

  • Critical 10.0
    CVE-2026-75874

    Sandbox escape in the Remote Settings Client component

    Sandbox escape in the Remote Settings Client component. This vulnerability was fixed in Firefox 154, Thunderbird 154, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 140.15, and Thunderbird 153.2.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi
  • Critical 9.8
    CVE-2026-84143

    Internally found bugs fixed in Thunderbird 155, Thunderbird ESR 153.2 and Thunderbird ESR 140.15

    Internally found bugs present in Thunderbird 154, Thunderbird ESR 153.1 and Thunderbird ESR 140.14. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have bee…

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi
  • Critical 9.8
    CVE-2026-92238

    Ambiguous parsing of mail headers

    A maliciously constructed mail header could lead to multiple fields being parsed as one, or potential memory safety violations. This vulnerability was fixed in Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.3.

    Mozilla Thunderbird thunderbird mozjs38 Debian Ubuntu
  • Critical 9.6
    CVE-2026-84119

    Sandbox escape due to use-after-free in the DOM: Navigation component

    Sandbox escape due to use-after-free in the DOM: Navigation component. This vulnerability was fixed in Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi
  • Critical 9.6
    CVE-2026-84121

    Sandbox escape due to use-after-free in the DOM: Security component

    Sandbox escape due to use-after-free in the DOM: Security component. This vulnerability was fixed in Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi
  • Critical 9.6
    CVE-2026-92018

    Sandbox escape in the DOM: Core & HTML component

    Sandbox escape in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 156, Firefox ESR 115.41, Firefox ESR 140.16, Firefox ESR 153.3, Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.3.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • Critical 9.6
    CVE-2026-92032

    Sandbox escape due to invalid pointer in the Graphics component

    Sandbox escape due to invalid pointer in the Graphics component. This vulnerability was fixed in Firefox 156, Firefox ESR 140.16, Firefox ESR 153.3, Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.3.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • Critical 9.1
    CVE-2026-84639

    Uninitialized memory in MIME parsing

    Triggering an error condition in certain MIME bodies would cause uninitialized memory to be used. This vulnerability was fixed in Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.

    Mozilla Thunderbird thunderbird thunderbird Debian Ubuntu
  • Critical 9.1
    CVE-2026-92240

    Out-of-bounds read in IMAP response parser

    A malicious or compromised IMAP server can trigger an out-of-bounds read in the IMAP response parser by sending an untagged '* ID' response, crashing Thunderbird. The affected parsing path is reachable before authentication. This vulnerability was fixed in Th…

    Mozilla Thunderbird thunderbird mozjs38 Debian Ubuntu
  • High 8.8
    CVE-2026-16365

    Privilege escalation in the DOM: Workers component

    Privilege escalation in the DOM: Workers component. This vulnerability was fixed in Firefox 153, Thunderbird 153, Firefox ESR 140.15, and Thunderbird 140.15.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi
  • High 8.8
    CVE-2026-84131

    Privilege escalation due to invalid pointer in the Graphics component

    Privilege escalation due to invalid pointer in the Graphics component. This vulnerability was fixed in Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi
  • High 8.8
    CVE-2026-92006

    Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component

    Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component. This vulnerability was fixed in Firefox 156, Firefox ESR 115.41, Firefox ESR 140.16, Firefox ESR 153.3, Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.…

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • High 8.8
    CVE-2026-92007

    Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component

    Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component. This vulnerability was fixed in Firefox 156, Firefox ESR 115.41, Firefox ESR 140.16, Firefox ESR 153.3, Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.…

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • High 8.8
    CVE-2026-92008

    Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component

    Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component. This vulnerability was fixed in Firefox 156, Firefox ESR 115.41, Firefox ESR 140.16, Firefox ESR 153.3, Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.…

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • High 8.8
    CVE-2026-92009

    Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component

    Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component. This vulnerability was fixed in Firefox 156, Firefox ESR 115.41, Firefox ESR 140.16, Firefox ESR 153.3, Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.…

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • High 8.8
    CVE-2026-92010

    Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component

    Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component. This vulnerability was fixed in Firefox 156, Firefox ESR 115.41, Firefox ESR 140.16, Firefox ESR 153.3, Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.…

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • High 8.8
    CVE-2026-92011

    Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component

    Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component. This vulnerability was fixed in Firefox 156, Firefox ESR 115.41, Firefox ESR 140.16, Firefox ESR 153.3, Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.…

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • High 8.8
    CVE-2026-92012

    Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component

    Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component. This vulnerability was fixed in Firefox 156, Firefox ESR 115.41, Firefox ESR 140.16, Firefox ESR 153.3, Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.…

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • High 8.8
    CVE-2026-92013

    Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component

    Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component. This vulnerability was fixed in Firefox 156, Firefox ESR 115.41, Firefox ESR 140.16, Firefox ESR 153.3, Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.…

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • High 8.8
    CVE-2026-92014

    Privilege escalation due to incorrect boundary conditions in the Graphics component

    Privilege escalation due to incorrect boundary conditions in the Graphics component. This vulnerability was fixed in Firefox ESR 115.41, Firefox ESR 140.16, and Thunderbird 140.16.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • High 8.8
    CVE-2026-92015

    Privilege escalation in the WebExtensions component

    Privilege escalation in the WebExtensions component. This vulnerability was fixed in Firefox 156, Firefox ESR 115.41, Firefox ESR 140.16, Firefox ESR 153.3, Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.3.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • High 8.8
    CVE-2026-92016

    Use-after-free in the Disability Access APIs component

    Use-after-free in the Disability Access APIs component. This vulnerability was fixed in Firefox 156, Firefox ESR 140.16, Firefox ESR 153.3, Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.3.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • High 8.8
    CVE-2026-92017

    Privilege escalation in the DOM: Service Workers component

    Privilege escalation in the DOM: Service Workers component. This vulnerability was fixed in Firefox 156, Firefox ESR 115.41, Firefox ESR 140.16, Firefox ESR 153.3, Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.3.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • High 8.8
    CVE-2026-92020

    Privilege escalation due to incorrect boundary conditions in the Graphics: WebRender component

    Privilege escalation due to incorrect boundary conditions in the Graphics: WebRender component. This vulnerability was fixed in Firefox 156, Firefox ESR 115.41, Firefox ESR 140.16, Firefox ESR 153.3, Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.3.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • High 8.8
    CVE-2026-92021

    Use-after-free in the JavaScript Engine: JIT component

    Use-after-free in the JavaScript Engine: JIT component. This vulnerability was fixed in Firefox ESR 140.16 and Thunderbird 140.16.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • High 8.8
    CVE-2026-92022

    Use-after-free in the DOM: HTML Parser component

    Use-after-free in the DOM: HTML Parser component. This vulnerability was fixed in Firefox 156, Firefox ESR 115.41, Firefox ESR 140.16, Firefox ESR 153.3, Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.3.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • High 8.8
    CVE-2026-92023

    Use-after-free in the XML component

    Use-after-free in the XML component. This vulnerability was fixed in Firefox 156, Firefox ESR 115.41, Firefox ESR 140.16, Firefox ESR 153.3, Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.3.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • High 8.8
    CVE-2026-92024

    Use-after-free in the SVG component

    Use-after-free in the SVG component. This vulnerability was fixed in Firefox 156, Firefox ESR 115.41, Firefox ESR 140.16, Firefox ESR 153.3, Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.3.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • High 8.8
    CVE-2026-92025

    Use-after-free in the DOM: Navigation component

    Use-after-free in the DOM: Navigation component. This vulnerability was fixed in Firefox 156, Firefox ESR 115.41, Firefox ESR 140.16, Firefox ESR 153.3, Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.3.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • High 8.8
    CVE-2026-92026

    Use-after-free in the Networking component

    Use-after-free in the Networking component. This vulnerability was fixed in Firefox 156, Firefox ESR 140.16, Firefox ESR 153.3, Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.3.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • High 8.8
    CVE-2026-92027

    Use-after-free in the DOM: Streams component

    Use-after-free in the DOM: Streams component. This vulnerability was fixed in Firefox 156, Firefox ESR 115.41, Firefox ESR 140.16, Firefox ESR 153.3, Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.3.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • High 8.8
    CVE-2026-92028

    Use-after-free in the DOM: Core & HTML component

    Use-after-free in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 156, Firefox ESR 115.41, Firefox ESR 140.16, Firefox ESR 153.3, Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.3.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • High 8.8
    CVE-2026-92029

    Use-after-free in the SVG component

    Use-after-free in the SVG component. This vulnerability was fixed in Firefox 156, Firefox ESR 115.41, Firefox ESR 140.16, Firefox ESR 153.3, Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.3.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • High 8.1
    CVE-2026-92019

    Mitigation bypass in the Remote Settings Client component

    Mitigation bypass in the Remote Settings Client component. This vulnerability was fixed in Firefox 156, Firefox ESR 115.41, Firefox ESR 140.16, Firefox ESR 153.3, Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.3.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • High 8.1
    CVE-2026-92239

    Buffer overrun in IMAP

    A maliciously constructed IMAP line could cause an out-of-bounds buffer read. This vulnerability was fixed in Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.3.

    Mozilla Thunderbird thunderbird mozjs38 Debian Ubuntu
  • High 7.5
    CVE-2026-84145

    Internally found bugs fixed in Thunderbird 155, Thunderbird ESR 153.2 and Thunderbird ESR 140.15

    Internally found bugs present in Thunderbird 154, Thunderbird ESR 153.1 and Thunderbird ESR 140.14. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have bee…

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi
  • High 7.5
    CVE-2026-84640

    One byte overflow read in mail parser

    A maliciously constructed mail header could lead to a one byte read past the end of a buffer. This vulnerability was fixed in Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.

    Mozilla Thunderbird thunderbird thunderbird Debian Ubuntu
  • High 7.5
    CVE-2026-84641

    Information disclosure due to malicious IMAP server response

    A malicious IMAP server can trigger use-after-free and heap-memory disclosure by sending a crafted ID response. Heap contents can ultimately be persisted to prefs.js. This vulnerability was fixed in Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.

    Mozilla Thunderbird thunderbird thunderbird Debian Ubuntu
  • Medium 6.5
    CVE-2026-92031

    Information disclosure in the Graphics: ImageLib component

    Information disclosure in the Graphics: ImageLib component. This vulnerability was fixed in Firefox 156, Firefox ESR 140.16, Firefox ESR 153.3, Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.3.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • Medium 5.4
    CVE-2026-84120

    Use-after-free in the Audio/Video component

    Use-after-free in the Audio/Video component. This vulnerability was fixed in Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi
  • Medium 5.4
    CVE-2026-84122

    Use-after-free in the Audio/Video component

    Use-after-free in the Audio/Video component. This vulnerability was fixed in Firefox 155, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi
  • Medium 5.4
    CVE-2026-84124

    Use-after-free in the DOM: Core & HTML component

    Use-after-free in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 155, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi
  • Medium 5.4
    CVE-2026-92030

    Mitigation bypass in the DOM: Copy & Paste and Drag & Drop component

    Mitigation bypass in the DOM: Copy & Paste and Drag & Drop component. This vulnerability was fixed in Firefox 156, Firefox ESR 140.16, Firefox ESR 153.3, Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.3.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu
  • Medium 5.3
    CVE-2026-92005

    Use-after-free in the Audio/Video: Web Codecs component

    Use-after-free in the Audio/Video: Web Codecs component. This vulnerability was fixed in Firefox 156, Firefox ESR 140.16, Firefox ESR 153.3, Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.3.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu

References

  • article
    https://access.redhat.com/security/updates/classification/#important
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2503504
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2517832
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2526753
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2526760
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2526764
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2526765
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2526767
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2526773
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2526778
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2526781
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2527113
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2527115
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2527116
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2533737
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2533740
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2533741
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2533742
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2533743
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2533747
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2533751
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2533753
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2533757
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2533758
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2533760
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2533762
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2533764
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2533769
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2533770
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2533771
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2533773
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2533774
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2533778
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2533779
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2533781
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2533786
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2533790
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2533791
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2533792