RHSA-2026:95596 - Security Advisory

Topic

An update for thunderbird is now available for Red Hat Enterprise Linux 9.6 Extended Update Support.

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):

• libexpat: denial of service via crafted XML input (CVE-2026-45186)
• firefox: Mitigation bypass in the Enterprise Policies component (CVE-2026-109764)
• firefox: Spoofing issue in the DOM: Web Serial component (CVE-2026-109770)
• firefox: Mitigation bypass in the File Handling component (CVE-2026-109783)
• firefox: thunderbird: Privilege escalation in the Application Update component (CVE-2026-109704)
• firefox: Use-after-free in the XML component (CVE-2026-109718)
• firefox: Information disclosure in the PDF Viewer component (CVE-2026-109742)
• firefox: Incorrect boundary conditions in the JavaScript Engine component (CVE-2026-109715)
• firefox: firefox: Sandbox escape via incorrect boundary conditions in Win32 widget (CVE-2026-109740)
• firefox: Use-after-free in the Storage: IndexedDB component (CVE-2026-109706)
• firefox: Use-after-free in the Crash Reporting component (CVE-2026-109713)
• firefox: Use-after-free in the DOM: Core & HTML component (CVE-2026-109724)
• firefox: Sandbox escape due to uninitialized memory in the DOM: Web Serial component (CVE-2026-109745)
• firefox: Mitigation bypass in the File Handling component (CVE-2026-109782)
• firefox: Information disclosure, privilege escalation in the Security: Process Sandboxing component (CVE-2026-109709)
• firefox: Sandbox escape, site isolation issue due to incorrect boundary conditions, use-after-free in the Networking component (CVE-2026-109705)
• firefox: Use-after-free in the Audio/Video: Playback component (CVE-2026-109738)
• firefox: Sandbox escape due to race condition in the Networking component (CVE-2026-109757)
• firefox: Use-after-free in the Storage: Bucket File System component (CVE-2026-109741)
• firefox: Use-after-free in the JavaScript Engine: JIT component (CVE-2026-109729)
• firefox: Other issue in the DOM: File component (CVE-2026-109744)
• firefox: Incorrect boundary conditions in the JavaScript Engine component (CVE-2026-109716)
• firefox: Race condition, use-after-free in the Graphics: CanvasWebGL component (CVE-2026-109719)
• firefox: Incorrect boundary conditions in the Layout component (CVE-2026-109753)
• firefox: Integer overflow in the Layout: Text and Fonts component (CVE-2026-109723)
• firefox: Privilege escalation in the DOM: Navigation component (CVE-2026-109756)
• firefox: JIT miscompilation in the JavaScript Engine: JIT component (CVE-2026-109733)
• firefox: thunderbird: Mitigation bypass in the DOM: Security component (CVE-2026-109734)
• firefox: Mitigation bypass in the File Handling component (CVE-2026-109763)
• firefox: Sandbox escape due to incorrect boundary conditions in the Networking component (CVE-2026-109708)
• firefox: Use-after-free in the DOM: Bindings (WebIDL) component (CVE-2026-109717)
• firefox: Use-after-free in the DOM: Workers component (CVE-2026-109752)
• firefox: Race condition in the XPCOM component (CVE-2026-109776)
• firefox: Sandbox escape due to use-after-free in the Networking component (CVE-2026-109707)
• firefox: Mitigation bypass in the Networking: HTTP component (CVE-2026-109760)
• firefox: JIT miscompilation in the JavaScript: WebAssembly component (CVE-2026-109720)
• firefox: Information disclosure in the Storage: IndexedDB component (CVE-2026-109777)
• firefox: Use-after-free in the SVG component (CVE-2026-109726)
• firefox: Integer overflow in the Graphics component (CVE-2026-109730)
• firefox: Use-after-free in the Audio/Video component (CVE-2026-109727)
• firefox: Mitigation bypass in the Enterprise Policies component (CVE-2026-109737)
• firefox: Mitigation bypass in the Enterprise Policies component (CVE-2026-109766)
• firefox: Use-after-free in the DOM: Streams component (CVE-2026-109732)
• firefox: Site isolation issue in the Networking component (CVE-2026-109759)
• firefox: Privilege escalation in the WebExtensions component (CVE-2026-109778)
• firefox: Incorrect boundary conditions in the SVG component (CVE-2026-109762)
• firefox: Race condition, use-after-free in the Graphics: Text component (CVE-2026-109765)
• firefox: Incorrect boundary conditions in the DOM: Editor component (CVE-2026-109754)
• firefox: Information disclosure in the Networking component (CVE-2026-109751)
• firefox: Use-after-free in the DOM: Core & HTML component (CVE-2026-109725)
• firefox: Sandbox escape due to uninitialized memory in the Graphics component (CVE-2026-109712)
• firefox: Use-after-free in the Graphics: Canvas2D component (CVE-2026-109711)
• firefox: Frame poisoning in the Layout component (CVE-2026-109736)
• firefox: JIT miscompilation in the JavaScript Engine: JIT component (CVE-2026-109722)
• firefox: Information disclosure in the Networking component (CVE-2026-109767)
• firefox: Denial-of-service in the WebRTC component (CVE-2026-109775)
• firefox: Use-after-free in the DOM: Animation component (CVE-2026-109728)
• firefox: Denial-of-service in the Printing: Output component (CVE-2026-109781)
• firefox: thunderbird: Use-after-free in the Graphics: Text component (CVE-2026-109710)
• firefox: thunderbird: Incorrect boundary conditions in the Graphics: Canvas2D component (CVE-2026-109731)
• firefox: Incorrect boundary conditions in the JavaScript Engine: JIT component (CVE-2026-109721)
• firefox: Privilege escalation in the Panning and Zooming component (CVE-2026-109743)

Bug Fix(es) and Enhancement(s):

• Thunderbird ESR 153 rebase [rhel-9.6.z] (JIRA:RHEL-175194)

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 - Extended Update Support 9.6 x86_64
• Red Hat Enterprise Linux Server - AUS 9.6 x86_64
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 9.6 s390x
• Red Hat Enterprise Linux for Power, little endian - Extended Update Support 9.6 ppc64le
• Red Hat Enterprise Linux for ARM 64 - Extended Update Support 9.6 aarch64
• Red Hat Enterprise Linux Server for Power LE - Update Services for SAP Solutions 9.6 ppc64le
• Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 9.6 x86_64
• Red Hat Enterprise Linux for ARM 64 - 4 years of updates 9.6 aarch64
• Red Hat Enterprise Linux for IBM z Systems - 4 years of updates 9.6 s390x
• Red Hat Enterprise Linux for x86_64 - Extended Life Cycle 9.6 x86_64
• Red Hat Enterprise Linux for ARM 64 - Extended Life Cycle 9.6 aarch64
• Red Hat Enterprise Linux for Power, little endian - Extended Life Cycle 9.6 ppc64le
• Red Hat Enterprise Linux for IBM z Systems - Extended Life Cycle 9.6 s390x

Fixes

• BZ - 2468575 - CVE-2026-45186 libexpat: denial of service via crafted XML input
• BZ - 2550393 - CVE-2026-109764 firefox: Mitigation bypass in the Enterprise Policies component
• BZ - 2550394 - CVE-2026-109770 firefox: Spoofing issue in the DOM: Web Serial component
• BZ - 2550396 - CVE-2026-109783 firefox: Mitigation bypass in the File Handling component
• BZ - 2550397 - CVE-2026-109704 firefox: thunderbird: Privilege escalation in the Application Update component
• BZ - 2550400 - CVE-2026-109718 firefox: Use-after-free in the XML component
• BZ - 2550401 - CVE-2026-109742 firefox: Information disclosure in the PDF Viewer component
• BZ - 2550403 - CVE-2026-109715 firefox: Incorrect boundary conditions in the JavaScript Engine component
• BZ - 2550404 - CVE-2026-109740 firefox: firefox: Sandbox escape via incorrect boundary conditions in Win32 widget
• BZ - 2550405 - CVE-2026-109706 firefox: Use-after-free in the Storage: IndexedDB component
• BZ - 2550406 - CVE-2026-109713 firefox: Use-after-free in the Crash Reporting component
• BZ - 2550408 - CVE-2026-109724 firefox: Use-after-free in the DOM: Core & HTML component
• BZ - 2550410 - CVE-2026-109745 firefox: Sandbox escape due to uninitialized memory in the DOM: Web Serial component
• BZ - 2550411 - CVE-2026-109782 firefox: Mitigation bypass in the File Handling component
• BZ - 2550412 - CVE-2026-109709 firefox: Information disclosure, privilege escalation in the Security: Process Sandboxing component
• BZ - 2550413 - CVE-2026-109705 firefox: Sandbox escape, site isolation issue due to incorrect boundary conditions, use-after-free in the Networking component
• BZ - 2550417 - CVE-2026-109738 firefox: Use-after-free in the Audio/Video: Playback component
• BZ - 2550418 - CVE-2026-109757 firefox: Sandbox escape due to race condition in the Networking component
• BZ - 2550419 - CVE-2026-109741 firefox: Use-after-free in the Storage: Bucket File System component
• BZ - 2550420 - CVE-2026-109729 firefox: Use-after-free in the JavaScript Engine: JIT component
• BZ - 2550421 - CVE-2026-109744 firefox: Other issue in the DOM: File component
• BZ - 2550422 - CVE-2026-109716 firefox: Incorrect boundary conditions in the JavaScript Engine component
• BZ - 2550424 - CVE-2026-109719 firefox: Race condition, use-after-free in the Graphics: CanvasWebGL component
• BZ - 2550425 - CVE-2026-109753 firefox: Incorrect boundary conditions in the Layout component
• BZ - 2550426 - CVE-2026-109723 firefox: Integer overflow in the Layout: Text and Fonts component
• BZ - 2550428 - CVE-2026-109756 firefox: Privilege escalation in the DOM: Navigation component
• BZ - 2550429 - CVE-2026-109733 firefox: JIT miscompilation in the JavaScript Engine: JIT component
• BZ - 2550430 - CVE-2026-109734 firefox: thunderbird: Mitigation bypass in the DOM: Security component
• BZ - 2550431 - CVE-2026-109763 firefox: Mitigation bypass in the File Handling component
• BZ - 2550432 - CVE-2026-109708 firefox: Sandbox escape due to incorrect boundary conditions in the Networking component
• BZ - 2550433 - CVE-2026-109717 firefox: Use-after-free in the DOM: Bindings (WebIDL) component
• BZ - 2550434 - CVE-2026-109752 firefox: Use-after-free in the DOM: Workers component
• BZ - 2550436 - CVE-2026-109776 firefox: Race condition in the XPCOM component
• BZ - 2550438 - CVE-2026-109707 firefox: Sandbox escape due to use-after-free in the Networking component
• BZ - 2550440 - CVE-2026-109760 firefox: Mitigation bypass in the Networking: HTTP component
• BZ - 2550442 - CVE-2026-109720 firefox: JIT miscompilation in the JavaScript: WebAssembly component
• BZ - 2550444 - CVE-2026-109777 firefox: Information disclosure in the Storage: IndexedDB component
• BZ - 2550446 - CVE-2026-109726 firefox: Use-after-free in the SVG component
• BZ - 2550450 - CVE-2026-109730 firefox: Integer overflow in the Graphics component
• BZ - 2550451 - CVE-2026-109727 firefox: Use-after-free in the Audio/Video component
• BZ - 2550452 - CVE-2026-109737 firefox: Mitigation bypass in the Enterprise Policies component
• BZ - 2550454 - CVE-2026-109766 firefox: Mitigation bypass in the Enterprise Policies component
• BZ - 2550455 - CVE-2026-109732 firefox: Use-after-free in the DOM: Streams component
• BZ - 2550458 - CVE-2026-109759 firefox: Site isolation issue in the Networking component
• BZ - 2550459 - CVE-2026-109778 firefox: Privilege escalation in the WebExtensions component
• BZ - 2550461 - CVE-2026-109762 firefox: Incorrect boundary conditions in the SVG component
• BZ - 2550463 - CVE-2026-109765 firefox: Race condition, use-after-free in the Graphics: Text component
• BZ - 2550464 - CVE-2026-109754 firefox: Incorrect boundary conditions in the DOM: Editor component
• BZ - 2550465 - CVE-2026-109751 firefox: Information disclosure in the Networking component
• BZ - 2550467 - CVE-2026-109725 firefox: Use-after-free in the DOM: Core & HTML component
• BZ - 2550468 - CVE-2026-109712 firefox: Sandbox escape due to uninitialized memory in the Graphics component
• BZ - 2550469 - CVE-2026-109711 firefox: Use-after-free in the Graphics: Canvas2D component
• BZ - 2550470 - CVE-2026-109736 firefox: Frame poisoning in the Layout component
• BZ - 2550471 - CVE-2026-109722 firefox: JIT miscompilation in the JavaScript Engine: JIT component
• BZ - 2550472 - CVE-2026-109767 firefox: Information disclosure in the Networking component
• BZ - 2550473 - CVE-2026-109775 firefox: Denial-of-service in the WebRTC component
• BZ - 2550474 - CVE-2026-109728 firefox: Use-after-free in the DOM: Animation component
• BZ - 2550475 - CVE-2026-109781 firefox: Denial-of-service in the Printing: Output component
• BZ - 2550476 - CVE-2026-109710 firefox: thunderbird: Use-after-free in the Graphics: Text component
• BZ - 2550477 - CVE-2026-109731 firefox: thunderbird: Incorrect boundary conditions in the Graphics: Canvas2D component
• BZ - 2550478 - CVE-2026-109721 firefox: Incorrect boundary conditions in the JavaScript Engine: JIT component
• BZ - 2550480 - CVE-2026-109743 firefox: Privilege escalation in the Panning and Zooming component

CVEs

• CVE-2026-45186
• CVE-2026-109704
• CVE-2026-109705
• CVE-2026-109706
• CVE-2026-109707
• CVE-2026-109708
• CVE-2026-109709
• CVE-2026-109710
• CVE-2026-109711
• CVE-2026-109712
• CVE-2026-109713
• CVE-2026-109715
• CVE-2026-109716
• CVE-2026-109717
• CVE-2026-109718
• CVE-2026-109719
• CVE-2026-109720
• CVE-2026-109721
• CVE-2026-109722
• CVE-2026-109723
• CVE-2026-109724
• CVE-2026-109725
• CVE-2026-109726
• CVE-2026-109727
• CVE-2026-109728
• CVE-2026-109729
• CVE-2026-109730
• CVE-2026-109731
• CVE-2026-109732
• CVE-2026-109733
• CVE-2026-109734
• CVE-2026-109736
• CVE-2026-109737
• CVE-2026-109738
• CVE-2026-109740
• CVE-2026-109741
• CVE-2026-109742
• CVE-2026-109743
• CVE-2026-109744
• CVE-2026-109745
• CVE-2026-109751
• CVE-2026-109752
• CVE-2026-109753
• CVE-2026-109754
• CVE-2026-109756
• CVE-2026-109757
• CVE-2026-109759
• CVE-2026-109760
• CVE-2026-109762
• CVE-2026-109763
• CVE-2026-109764
• CVE-2026-109765
• CVE-2026-109766
• CVE-2026-109767
• CVE-2026-109770
• CVE-2026-109775
• CVE-2026-109776
• CVE-2026-109777
• CVE-2026-109778
• CVE-2026-109781
• CVE-2026-109782
• CVE-2026-109783

References

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