RLSA-2026:3515 — Important: thunderbird security update

Summary

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.

Fixed packages 1

Release	Package	Fixed in
Rocky Linux · 8	thunderbird	0:140.8.0-1.el8_10

Vulnerabilities 38

Critical 10.0

CVE-2026-2760

Sandbox escape due to incorrect boundary conditions in the Graphics: WebRender component

Sandbox escape due to incorrect boundary conditions in the Graphics: WebRender component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 24, 2026
Critical 10.0

CVE-2026-2761

Sandbox escape in the Graphics: WebRender component

Sandbox escape in the Graphics: WebRender component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 24, 2026
Critical 10.0

CVE-2026-2768

Sandbox escape in the Storage: IndexedDB component

Sandbox escape in the Storage: IndexedDB component. This vulnerability was fixed in Firefox 148, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 24, 2026
Critical 10.0

CVE-2026-2776

Sandbox escape due to incorrect boundary conditions in the Telemetry component in External Software

Sandbox escape due to incorrect boundary conditions in the Telemetry component in External Software. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 24, 2026
Critical 10.0

CVE-2026-2778

Sandbox escape due to incorrect boundary conditions in the DOM: Core & HTML component

Sandbox escape due to incorrect boundary conditions in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 24, 2026
Critical 9.8

CVE-2026-2757

Incorrect boundary conditions in the WebRTC: Audio/Video component

Incorrect boundary conditions in the WebRTC: Audio/Video component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 24, 2026
Critical 9.8

CVE-2026-2758

Use-after-free in the JavaScript: GC component

Use-after-free in the JavaScript: GC component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 24, 2026
Critical 9.8

CVE-2026-2759

Incorrect boundary conditions in the Graphics: ImageLib component

Incorrect boundary conditions in the Graphics: ImageLib component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 24, 2026
Critical 9.8

CVE-2026-2762

Integer overflow in the JavaScript: Standard Library component

Integer overflow in the JavaScript: Standard Library component. This vulnerability was fixed in Firefox 148, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 24, 2026
Critical 9.8

CVE-2026-2763 Public exploit

Use-after-free in the JavaScript Engine component

Use-after-free in the JavaScript Engine component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 24, 2026
Critical 9.8

CVE-2026-2764 Public exploit

JIT miscompilation, use-after-free in the JavaScript Engine: JIT component

JIT miscompilation, use-after-free in the JavaScript Engine: JIT component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 24, 2026
Critical 9.8

CVE-2026-2765

Use-after-free in the JavaScript Engine component

Use-after-free in the JavaScript Engine component. This vulnerability was fixed in Firefox 148, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 24, 2026
Critical 9.8

CVE-2026-2766 Public exploit

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

Use-after-free in the JavaScript Engine: JIT component. This vulnerability was fixed in Firefox 148, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 24, 2026
Critical 9.8

CVE-2026-2771

Undefined behavior in the DOM: Core & HTML component

Undefined behavior in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 24, 2026
Critical 9.8

CVE-2026-2773

Incorrect boundary conditions in the Web Audio component

Incorrect boundary conditions in the Web Audio component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 24, 2026
Critical 9.8

CVE-2026-2775

Mitigation bypass in the DOM: HTML Parser component

Mitigation bypass in the DOM: HTML Parser component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 24, 2026
Critical 9.8

CVE-2026-2777

Privilege escalation in the Messaging System component

Privilege escalation in the Messaging System component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 24, 2026
Critical 9.8

CVE-2026-2779

Incorrect boundary conditions in the Networking: JAR component

Incorrect boundary conditions in the Networking: JAR component. This vulnerability was fixed in Firefox 148, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 24, 2026
Critical 9.8

CVE-2026-2784

Mitigation bypass in the DOM: Security component

Mitigation bypass in the DOM: Security component. This vulnerability was fixed in Firefox 148, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 24, 2026
Critical 9.8

CVE-2026-2788

Incorrect boundary conditions in the Audio/Video: GMP component

Incorrect boundary conditions in the Audio/Video: GMP component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 24, 2026
Critical 9.8

CVE-2026-2791

Mitigation bypass in the Networking: Cache component

Mitigation bypass in the Networking: Cache component. This vulnerability was fixed in Firefox 148, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 24, 2026
Critical 9.8

CVE-2026-2792

Memory safety bugs fixed in Firefox ESR 140.8, Thunderbird ESR 140.8, Firefox 148 and Thunderbird 148

Memory safety bugs present in Firefox ESR 140.7, Thunderbird ESR 140.7, Firefox 147 and Thunderbird 147. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary co…

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 24, 2026
Critical 9.8

CVE-2026-2793

Memory safety bugs fixed in Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird ESR 140.8, Firefox 148 and Thunderbird 148

Memory safety bugs present in Firefox ESR 115.32, Firefox ESR 140.7, Thunderbird ESR 140.7, Firefox 147 and Thunderbird 147. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited…

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 24, 2026
High 8.8

CVE-2026-2447

Heap buffer overflow in libvpx

Heap buffer overflow in libvpx. This vulnerability was fixed in Firefox 147.0.4, Firefox ESR 140.7.1, Firefox ESR 115.32.1, Thunderbird 140.7.2, and Thunderbird 147.0.2.

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 16, 2026
High 8.8

CVE-2026-2767

Use-after-free in the JavaScript: WebAssembly component

Use-after-free in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox 148, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 24, 2026
High 8.8

CVE-2026-2769

Use-after-free in the Storage: IndexedDB component

Use-after-free in the Storage: IndexedDB component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 24, 2026
High 8.8

CVE-2026-2770

Use-after-free in the DOM: Bindings (WebIDL) component

Use-after-free in the DOM: Bindings (WebIDL) component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 24, 2026
High 8.8

CVE-2026-2772

Use-after-free in the Audio/Video: Playback component

Use-after-free in the Audio/Video: Playback component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 24, 2026
High 8.8

CVE-2026-2774

Integer overflow in the Audio/Video component

Integer overflow in the Audio/Video component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 24, 2026
High 8.8

CVE-2026-2780

Privilege escalation in the Netmonitor component

Privilege escalation in the Netmonitor component. This vulnerability was fixed in Firefox 148, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 24, 2026
High 8.8

CVE-2026-2781

Integer overflow in the Libraries component in NSS

Integer overflow in the Libraries component in NSS. This vulnerability was fixed in Firefox 148, Firefox ESR 140.8, Thunderbird 148, Thunderbird 140.8, and Firefox ESR 115.35.

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 24, 2026
High 8.8

CVE-2026-2782

Privilege escalation in the Netmonitor component

Privilege escalation in the Netmonitor component. This vulnerability was fixed in Firefox 148, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 24, 2026
High 8.8

CVE-2026-2785

Invalid pointer in the JavaScript Engine component

Invalid pointer in the JavaScript Engine component. This vulnerability was fixed in Firefox 148, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 24, 2026
High 8.8

CVE-2026-2786

Use-after-free in the JavaScript Engine component

Use-after-free in the JavaScript Engine component. This vulnerability was fixed in Firefox 148, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 24, 2026
High 8.8

CVE-2026-2787

Use-after-free in the DOM: Window and Location component

Use-after-free in the DOM: Window and Location component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 24, 2026
High 8.8

CVE-2026-2789

Use-after-free in the Graphics: ImageLib component

Use-after-free in the Graphics: ImageLib component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 24, 2026
High 8.8

CVE-2026-2790

Same-origin policy bypass in the Networking: JAR component

Same-origin policy bypass in the Networking: JAR component. This vulnerability was fixed in Firefox 148, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 24, 2026
Medium 6.5

CVE-2026-2783

Information disclosure due to JIT miscompilation in the JavaScript Engine: JIT component

Information disclosure due to JIT miscompilation in the JavaScript Engine: JIT component. This vulnerability was fixed in Firefox 148, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi

Feb 24, 2026

References

report
https://bugzilla.redhat.com/show_bug.cgi?id=2440219
report
https://bugzilla.redhat.com/show_bug.cgi?id=2442284
report
https://bugzilla.redhat.com/show_bug.cgi?id=2442287
report
https://bugzilla.redhat.com/show_bug.cgi?id=2442288
report
https://bugzilla.redhat.com/show_bug.cgi?id=2442290
report
https://bugzilla.redhat.com/show_bug.cgi?id=2442291
report
https://bugzilla.redhat.com/show_bug.cgi?id=2442292
report
https://bugzilla.redhat.com/show_bug.cgi?id=2442294
report
https://bugzilla.redhat.com/show_bug.cgi?id=2442295
report
https://bugzilla.redhat.com/show_bug.cgi?id=2442297
report
https://bugzilla.redhat.com/show_bug.cgi?id=2442298
report
https://bugzilla.redhat.com/show_bug.cgi?id=2442300
report
https://bugzilla.redhat.com/show_bug.cgi?id=2442302
report
https://bugzilla.redhat.com/show_bug.cgi?id=2442304
report
https://bugzilla.redhat.com/show_bug.cgi?id=2442307
report
https://bugzilla.redhat.com/show_bug.cgi?id=2442308
report
https://bugzilla.redhat.com/show_bug.cgi?id=2442309
report
https://bugzilla.redhat.com/show_bug.cgi?id=2442312
report
https://bugzilla.redhat.com/show_bug.cgi?id=2442313
report
https://bugzilla.redhat.com/show_bug.cgi?id=2442314
report
https://bugzilla.redhat.com/show_bug.cgi?id=2442316
report
https://bugzilla.redhat.com/show_bug.cgi?id=2442318
report
https://bugzilla.redhat.com/show_bug.cgi?id=2442319
report
https://bugzilla.redhat.com/show_bug.cgi?id=2442320
report
https://bugzilla.redhat.com/show_bug.cgi?id=2442322
report
https://bugzilla.redhat.com/show_bug.cgi?id=2442324
report
https://bugzilla.redhat.com/show_bug.cgi?id=2442325
report
https://bugzilla.redhat.com/show_bug.cgi?id=2442326
report
https://bugzilla.redhat.com/show_bug.cgi?id=2442327
report
https://bugzilla.redhat.com/show_bug.cgi?id=2442328
report
https://bugzilla.redhat.com/show_bug.cgi?id=2442329
report
https://bugzilla.redhat.com/show_bug.cgi?id=2442331
report
https://bugzilla.redhat.com/show_bug.cgi?id=2442333
report
https://bugzilla.redhat.com/show_bug.cgi?id=2442334
report
https://bugzilla.redhat.com/show_bug.cgi?id=2442335
report
https://bugzilla.redhat.com/show_bug.cgi?id=2442337
report
https://bugzilla.redhat.com/show_bug.cgi?id=2442342
report
https://bugzilla.redhat.com/show_bug.cgi?id=2442343