RHSA-2026:3981 - Security Advisory

Topic

An update for thunderbird is now available for Red Hat Enterprise Linux 9.4 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):

• libvpx: Heap buffer overflow in libvpx (CVE-2026-2447)
• firefox: Invalid pointer in the JavaScript Engine component (CVE-2026-2785)
• firefox: Memory safety bugs fixed in Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird ESR 140.8, Firefox 148 and Thunderbird 148 (CVE-2026-2793)
• firefox: Undefined behavior in the DOM: Core & HTML component (CVE-2026-2771)
• firefox: Integer overflow in the Audio/Video component (CVE-2026-2774)
• firefox: Sandbox escape due to incorrect boundary conditions in the Telemetry component in External Software (CVE-2026-2776)
• firefox: Integer overflow in the Libraries component in NSS (CVE-2026-2781)
• firefox: Use-after-free in the JavaScript Engine: JIT component (CVE-2026-2766)
• firefox: Use-after-free in the Storage: IndexedDB component (CVE-2026-2769)
• firefox: Use-after-free in the DOM: Window and Location component (CVE-2026-2787)
• firefox: Sandbox escape in the Storage: IndexedDB component (CVE-2026-2768)
• firefox: Information disclosure due to JIT miscompilation in the JavaScript Engine: JIT component (CVE-2026-2783)
• firefox: Incorrect boundary conditions in the Audio/Video: GMP component (CVE-2026-2788)
• firefox: Mitigation bypass in the DOM: Security component (CVE-2026-2784)
• firefox: Incorrect boundary conditions in the Graphics: ImageLib component (CVE-2026-2759)
• firefox: Integer overflow in the JavaScript: Standard Library component (CVE-2026-2762)
• firefox: Sandbox escape in the Graphics: WebRender component (CVE-2026-2761)
• firefox: Privilege escalation in the Messaging System component (CVE-2026-2777)
• firefox: Same-origin policy bypass in the Networking: JAR component (CVE-2026-2790)
• firefox: Mitigation bypass in the DOM: HTML Parser component (CVE-2026-2775)
• firefox: Use-after-free in the JavaScript Engine component (CVE-2026-2763)
• firefox: Memory safety bugs fixed in Firefox ESR 140.8, Thunderbird ESR 140.8, Firefox 148 and Thunderbird 148 (CVE-2026-2792)
• firefox: Incorrect boundary conditions in the Web Audio component (CVE-2026-2773)
• firefox: Use-after-free in the JavaScript Engine component (CVE-2026-2786)
• firefox: Use-after-free in the Graphics: ImageLib component (CVE-2026-2789)
• firefox: thunderbird: Incorrect boundary conditions in the WebRTC: Audio/Video component (CVE-2026-2757)
• firefox: Sandbox escape due to incorrect boundary conditions in the Graphics: WebRender component (CVE-2026-2760)
• firefox: Use-after-free in the Audio/Video: Playback component (CVE-2026-2772)
• firefox: Incorrect boundary conditions in the Networking: JAR component (CVE-2026-2779)
• firefox: Use-after-free in the JavaScript: WebAssembly component (CVE-2026-2767)
• firefox: JIT miscompilation, use-after-free in the JavaScript Engine: JIT component (CVE-2026-2764)
• firefox: Privilege escalation in the Netmonitor component (CVE-2026-2782)
• firefox: Use-after-free in the JavaScript Engine component (CVE-2026-2765)
• firefox: Privilege escalation in the Netmonitor component (CVE-2026-2780)
• firefox: Sandbox escape due to incorrect boundary conditions in the DOM: Core & HTML component (CVE-2026-2778)
• firefox: Use-after-free in the JavaScript: GC component (CVE-2026-2758)
• firefox: Mitigation bypass in the Networking: Cache component (CVE-2026-2791)
• firefox: Use-after-free in the DOM: Bindings (WebIDL) component (CVE-2026-2770)

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 9.4 x86_64
• Red Hat Enterprise Linux Server - AUS 9.4 x86_64
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 9.4 s390x
• Red Hat Enterprise Linux for Power, little endian - Extended Update Support 9.4 ppc64le
• Red Hat Enterprise Linux for ARM 64 - Extended Update Support 9.4 aarch64
• Red Hat Enterprise Linux Server for Power LE - Update Services for SAP Solutions 9.4 ppc64le
• Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 9.4 x86_64
• Red Hat Enterprise Linux for ARM 64 - 4 years of updates 9.4 aarch64
• Red Hat Enterprise Linux for IBM z Systems - 4 years of updates 9.4 s390x

Fixes

• BZ - 2440219 - CVE-2026-2447 libvpx: Heap buffer overflow in libvpx
• BZ - 2442284 - CVE-2026-2785 firefox: thunderbird: Invalid pointer in the JavaScript Engine component
• BZ - 2442287 - CVE-2026-2793 firefox: thunderbird: Memory safety bugs fixed in Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird ESR 140.8, Firefox 148 and Thunderbird 148
• BZ - 2442288 - CVE-2026-2771 firefox: thunderbird: Undefined behavior in the DOM: Core & HTML component
• BZ - 2442290 - CVE-2026-2774 firefox: thunderbird: Integer overflow in the Audio/Video component
• BZ - 2442291 - CVE-2026-2776 firefox: thunderbird: Sandbox escape due to incorrect boundary conditions in the Telemetry component in External Software
• BZ - 2442292 - CVE-2026-2781 firefox: thunderbird: Integer overflow in the Libraries component in NSS
• BZ - 2442294 - CVE-2026-2766 firefox: thunderbird: Use-after-free in the JavaScript Engine: JIT component
• BZ - 2442295 - CVE-2026-2769 firefox: thunderbird: Use-after-free in the Storage: IndexedDB component
• BZ - 2442297 - CVE-2026-2787 firefox: thunderbird: Use-after-free in the DOM: Window and Location component
• BZ - 2442298 - CVE-2026-2768 firefox: thunderbird: Sandbox escape in the Storage: IndexedDB component
• BZ - 2442300 - CVE-2026-2783 firefox: thunderbird: Information disclosure due to JIT miscompilation in the JavaScript Engine: JIT component
• BZ - 2442302 - CVE-2026-2788 firefox: thunderbird: Incorrect boundary conditions in the Audio/Video: GMP component
• BZ - 2442304 - CVE-2026-2784 firefox: thunderbird: Mitigation bypass in the DOM: Security component
• BZ - 2442307 - CVE-2026-2759 firefox: thunderbird: Incorrect boundary conditions in the Graphics: ImageLib component
• BZ - 2442308 - CVE-2026-2762 firefox: thunderbird: Integer overflow in the JavaScript: Standard Library component
• BZ - 2442309 - CVE-2026-2761 firefox: thunderbird: Sandbox escape in the Graphics: WebRender component
• BZ - 2442312 - CVE-2026-2777 firefox: thunderbird: Privilege escalation in the Messaging System component
• BZ - 2442313 - CVE-2026-2790 firefox: thunderbird: Same-origin policy bypass in the Networking: JAR component
• BZ - 2442314 - CVE-2026-2775 firefox: thunderbird: Mitigation bypass in the DOM: HTML Parser component
• BZ - 2442316 - CVE-2026-2763 firefox: thunderbird: Use-after-free in the JavaScript Engine component
• BZ - 2442318 - CVE-2026-2792 firefox: thunderbird: Memory safety bugs fixed in Firefox ESR 140.8, Thunderbird ESR 140.8, Firefox 148 and Thunderbird 148
• BZ - 2442319 - CVE-2026-2773 firefox: thunderbird: Incorrect boundary conditions in the Web Audio component
• BZ - 2442320 - CVE-2026-2786 firefox: thunderbird: Use-after-free in the JavaScript Engine component
• BZ - 2442322 - CVE-2026-2789 firefox: thunderbird: Use-after-free in the Graphics: ImageLib component
• BZ - 2442324 - CVE-2026-2757 firefox: thunderbird: Incorrect boundary conditions in the WebRTC: Audio/Video component
• BZ - 2442325 - CVE-2026-2760 firefox: thunderbird: Sandbox escape due to incorrect boundary conditions in the Graphics: WebRender component
• BZ - 2442326 - CVE-2026-2772 firefox: thunderbird: Use-after-free in the Audio/Video: Playback component
• BZ - 2442327 - CVE-2026-2779 firefox: thunderbird: Incorrect boundary conditions in the Networking: JAR component
• BZ - 2442328 - CVE-2026-2767 firefox: thunderbird: Use-after-free in the JavaScript: WebAssembly component
• BZ - 2442329 - CVE-2026-2764 firefox: thunderbird: JIT miscompilation, use-after-free in the JavaScript Engine: JIT component
• BZ - 2442331 - CVE-2026-2782 firefox: thunderbird: Privilege escalation in the Netmonitor component
• BZ - 2442333 - CVE-2026-2765 firefox: thunderbird: Use-after-free in the JavaScript Engine component
• BZ - 2442334 - CVE-2026-2780 firefox: thunderbird: Privilege escalation in the Netmonitor component
• BZ - 2442335 - CVE-2026-2778 firefox: thunderbird: Sandbox escape due to incorrect boundary conditions in the DOM: Core & HTML component
• BZ - 2442337 - CVE-2026-2758 firefox: thunderbird: Use-after-free in the JavaScript: GC component
• BZ - 2442342 - CVE-2026-2791 firefox: thunderbird: Mitigation bypass in the Networking: Cache component
• BZ - 2442343 - CVE-2026-2770 firefox: thunderbird: Use-after-free in the DOM: Bindings (WebIDL) component

CVEs

• CVE-2026-2447
• CVE-2026-2757
• CVE-2026-2758
• CVE-2026-2759
• CVE-2026-2760
• CVE-2026-2761
• CVE-2026-2762
• CVE-2026-2763
• CVE-2026-2764
• CVE-2026-2765
• CVE-2026-2766
• CVE-2026-2767
• CVE-2026-2768
• CVE-2026-2769
• CVE-2026-2770
• CVE-2026-2771
• CVE-2026-2772
• CVE-2026-2773
• CVE-2026-2774
• CVE-2026-2775
• CVE-2026-2776
• CVE-2026-2777
• CVE-2026-2778
• CVE-2026-2779
• CVE-2026-2780
• CVE-2026-2781
• CVE-2026-2782
• CVE-2026-2783
• CVE-2026-2784
• CVE-2026-2785
• CVE-2026-2786
• CVE-2026-2787
• CVE-2026-2788
• CVE-2026-2789
• CVE-2026-2790
• CVE-2026-2791
• CVE-2026-2792
• CVE-2026-2793

References

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