RHSA-2026:13537 - 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: Incorrect boundary conditions in the Libraries component in NSS (CVE-2026-6772)
• firefox: thunderbird: Use-after-free in the JavaScript Engine component (CVE-2026-6754)
• firefox: thunderbird: Spoofing issue in the DOM: Core & HTML component (CVE-2026-6762)
• firefox: thunderbird: Incorrect boundary conditions in the WebRTC component (CVE-2026-6752)
• firefox: thunderbird: Other issue in the Storage: IndexedDB component (CVE-2026-6770)
• firefox: thunderbird: Invalid pointer in the JavaScript: WebAssembly component (CVE-2026-6757)
• firefox: thunderbird: Other issue in the Libraries component in NSS (CVE-2026-6767)
• firefox: thunderbird: Memory safety bugs fixed in Firefox ESR 140.10, Thunderbird ESR 140.10, Firefox 150 and Thunderbird 150 (CVE-2026-6786)
• firefox: thunderbird: Incorrect boundary conditions in the WebRTC component (CVE-2026-6753)
• firefox: thunderbird: Use-after-free in the Widget: Cocoa component (CVE-2026-6759)
• firefox: thunderbird: Use-after-free in the WebRTC component (CVE-2026-6747)
• firefox: thunderbird: Information disclosure due to uninitialized memory in the Graphics: Canvas2D component (CVE-2026-6749)
• firefox: thunderbird: Incorrect boundary conditions in the Libraries component in NSS (CVE-2026-6766)
• firefox: thunderbird: Privilege escalation in the Networking component (CVE-2026-6761)
• firefox: thunderbird: Mitigation bypass in the File Handling component (CVE-2026-6763)
• firefox: thunderbird: Privilege escalation in the Graphics: WebRender component (CVE-2026-6750)
• firefox: thunderbird: Uninitialized memory in the Audio/Video: Web Codecs component (CVE-2026-6748)
• firefox: thunderbird: Memory safety bugs fixed in Firefox ESR 115.35, Firefox ESR 140.10, Thunderbird ESR 140.10, Firefox 150 and Thunderbird 150 (CVE-2026-6785)
• firefox: thunderbird: Mitigation bypass in the DOM: Security component (CVE-2026-6771)
• firefox: thunderbird: Incorrect boundary conditions in the DOM: Device Interfaces component (CVE-2026-6764)
• firefox: thunderbird: Information disclosure in the Form Autofill component (CVE-2026-6765)
• firefox: thunderbird: Privilege escalation in the Debugger component (CVE-2026-6769)
• firefox: thunderbird: Uninitialized memory in the Audio/Video: Web Codecs component (CVE-2026-6751)
• firefox: thunderbird: Incorrect boundary conditions in the WebRTC: Networking component (CVE-2026-6776)
• firefox: thunderbird: Use-after-free in the DOM: Core & HTML component (CVE-2026-6746)

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 - 2460074 - CVE-2026-6772 firefox: thunderbird: Incorrect boundary conditions in the Libraries component in NSS
• BZ - 2460075 - CVE-2026-6754 firefox: thunderbird: Use-after-free in the JavaScript Engine component
• BZ - 2460076 - CVE-2026-6762 firefox: thunderbird: Spoofing issue in the DOM: Core & HTML component
• BZ - 2460078 - CVE-2026-6752 firefox: thunderbird: Incorrect boundary conditions in the WebRTC component
• BZ - 2460079 - CVE-2026-6770 firefox: thunderbird: Other issue in the Storage: IndexedDB component
• BZ - 2460085 - CVE-2026-6757 firefox: thunderbird: Invalid pointer in the JavaScript: WebAssembly component
• BZ - 2460086 - CVE-2026-6767 firefox: thunderbird: Other issue in the Libraries component in NSS
• BZ - 2460088 - CVE-2026-6786 firefox: thunderbird: Memory safety bugs fixed in Firefox ESR 140.10, Thunderbird ESR 140.10, Firefox 150 and Thunderbird 150
• BZ - 2460092 - CVE-2026-6753 firefox: thunderbird: Incorrect boundary conditions in the WebRTC component
• BZ - 2460094 - CVE-2026-6759 firefox: thunderbird: Use-after-free in the Widget: Cocoa component
• BZ - 2460095 - CVE-2026-6747 firefox: thunderbird: Use-after-free in the WebRTC component
• BZ - 2460096 - CVE-2026-6749 firefox: thunderbird: Information disclosure due to uninitialized memory in the Graphics: Canvas2D component
• BZ - 2460097 - CVE-2026-6766 firefox: thunderbird: Incorrect boundary conditions in the Libraries component in NSS
• BZ - 2460099 - CVE-2026-6761 firefox: thunderbird: Privilege escalation in the Networking component
• BZ - 2460101 - CVE-2026-6763 firefox: thunderbird: Mitigation bypass in the File Handling component
• BZ - 2460102 - CVE-2026-6750 firefox: thunderbird: Privilege escalation in the Graphics: WebRender component
• BZ - 2460103 - CVE-2026-6748 firefox: thunderbird: Uninitialized memory in the Audio/Video: Web Codecs component
• BZ - 2460104 - CVE-2026-6785 firefox: thunderbird: Memory safety bugs fixed in Firefox ESR 115.35, Firefox ESR 140.10, Thunderbird ESR 140.10, Firefox 150 and Thunderbird 150
• BZ - 2460105 - CVE-2026-6771 firefox: thunderbird: Mitigation bypass in the DOM: Security component
• BZ - 2460106 - CVE-2026-6764 firefox: thunderbird: Incorrect boundary conditions in the DOM: Device Interfaces component
• BZ - 2460107 - CVE-2026-6765 firefox: thunderbird: Information disclosure in the Form Autofill component
• BZ - 2460108 - CVE-2026-6769 firefox: thunderbird: Privilege escalation in the Debugger component
• BZ - 2460109 - CVE-2026-6751 firefox: thunderbird: Uninitialized memory in the Audio/Video: Web Codecs component
• BZ - 2460110 - CVE-2026-6776 firefox: thunderbird: Incorrect boundary conditions in the WebRTC: Networking component
• BZ - 2460112 - CVE-2026-6746 firefox: thunderbird: Use-after-free in the DOM: Core & HTML component

CVEs

• CVE-2026-6746
• CVE-2026-6747
• CVE-2026-6748
• CVE-2026-6749
• CVE-2026-6750
• CVE-2026-6751
• CVE-2026-6752
• CVE-2026-6753
• CVE-2026-6754
• CVE-2026-6757
• CVE-2026-6759
• CVE-2026-6761
• CVE-2026-6762
• CVE-2026-6763
• CVE-2026-6764
• CVE-2026-6765
• CVE-2026-6766
• CVE-2026-6767
• CVE-2026-6769
• CVE-2026-6770
• CVE-2026-6771
• CVE-2026-6772
• CVE-2026-6776
• CVE-2026-6785
• CVE-2026-6786

References

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