RHSA-2026:49921 - Security Advisory

Topic

An update for thunderbird is now available for Red Hat Enterprise Linux 9.

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: Site isolation issue in the DOM: Navigation component (CVE-2026-15719)
• firefox: thunderbird: Invalid pointer in the JavaScript: WebAssembly component (CVE-2026-15718)
• firefox: thunderbird: Mitigation bypass in the Enterprise Policies component (CVE-2026-16390)
• firefox: thunderbird: Incorrect boundary conditions in the Audio/Video: cubeb component (CVE-2026-16350)
• firefox: thunderbird: Information disclosure in the Storage: IndexedDB component (CVE-2026-16391)
• firefox: thunderbird: Site isolation issue in the Networking: HTTP component (CVE-2026-16375)
• firefox: thunderbird: Sandbox escape due to use-after-free in the Disability Access APIs component (CVE-2026-16356)
• firefox: thunderbird: JIT miscompilation in the JavaScript: WebAssembly component (CVE-2026-16363)
• firefox: thunderbird: Memory safety bugs fixed in Firefox ESR 140.13 and Firefox 153 (CVE-2026-16412)
• firefox: thunderbird: Same-origin policy bypass in the Networking: DNS component (CVE-2026-16381)
• firefox: thunderbird: JIT miscompilation in the JavaScript Engine: JIT component (CVE-2026-16355)
• firefox: thunderbird: Memory safety bugs fixed in Firefox ESR 115.38 and Firefox ESR 140.13 (CVE-2026-16361)
• firefox: thunderbird: Sandbox escape due to use-after-free in the Disability Access APIs component (CVE-2026-16352)
• firefox: thunderbird: Incorrect boundary conditions in the JavaScript: WebAssembly component (CVE-2026-16368)
• firefox: thunderbird: Mitigation bypass in the PDF Viewer component (CVE-2026-16377)
• firefox: thunderbird: Memory safety bugs fixed in Firefox ESR 115.38, Firefox ESR 140.13 and Firefox 153 (CVE-2026-16360)
• firefox: thunderbird: Use-after-free in the WebRTC: Audio/Video component (CVE-2026-16362)
• firefox: thunderbird: Site isolation issue in the Graphics: WebRender component (CVE-2026-16358)
• firefox: thunderbird: Site isolation issue in the Networking component (CVE-2026-16387)
• firefox: thunderbird: Same-origin policy bypass in the DOM: Navigation component (CVE-2026-16349)
• firefox: thunderbird: Incorrect boundary conditions in the Graphics component (CVE-2026-16357)
• firefox: thunderbird: Sandbox escape due to use-after-free in the DOM: Navigation component (CVE-2026-16351)
• firefox: thunderbird: Privilege escalation in the DOM: Navigation component (CVE-2026-16371)
• firefox: thunderbird: Privilege escalation in the DOM: Content Processes component (CVE-2026-16379)
• firefox: thunderbird: Information disclosure in the Graphics: ImageLib component (CVE-2026-16354)
• firefox: thunderbird: Information disclosure in the Framework component in DevTools (CVE-2026-16374)
• firefox: thunderbird: Incorrect boundary conditions in the Audio/Video: GMP component (CVE-2026-16359)
• firefox: thunderbird: Mitigation bypass in the DOM: Networking component (CVE-2026-16383)
• firefox: thunderbird: Integer overflow in the JavaScript: WebAssembly component (CVE-2026-16369)
• firefox: thunderbird: Invalid pointer in the DOM: Bindings (WebIDL) component (CVE-2026-16353)
• firefox: thunderbird: Privilege escalation in WebExtensions (CVE-2026-16396)
• firefox: thunderbird: Information disclosure in the Networking: WebSockets component (CVE-2026-16405)
• thunderbird: Off-by-one out of bounds read in MIME header parser for forwarding (CVE-2026-14899)

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 9 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 9.8 x86_64
• Red Hat Enterprise Linux for IBM z Systems 9 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 9.8 s390x
• Red Hat Enterprise Linux for Power, little endian 9 ppc64le
• Red Hat Enterprise Linux for Power, little endian - Extended Update Support 9.8 ppc64le
• Red Hat Enterprise Linux for ARM 64 9 aarch64
• Red Hat Enterprise Linux for ARM 64 - Extended Update Support 9.8 aarch64
• Red Hat Enterprise Linux Server for Power LE - Update Services for SAP Solutions 9.8 ppc64le
• Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 9.8 x86_64
• Red Hat Enterprise Linux for ARM 64 - 4 years of updates 9.8 aarch64
• Red Hat Enterprise Linux for IBM z Systems - 4 years of updates 9.8 s390x
• Red Hat Enterprise Linux for x86_64 - Extended Life Cycle 9.8 x86_64
• Red Hat Enterprise Linux for ARM 64 - Extended Life Cycle 9.8 aarch64
• Red Hat Enterprise Linux for Power, little endian - Extended Life Cycle 9.8 ppc64le
• Red Hat Enterprise Linux for IBM z Systems - Extended Life Cycle 9.8 s390x

Fixes

• BZ - 2499973 - CVE-2026-15719 firefox: thunderbird: Site isolation issue in the DOM: Navigation component
• BZ - 2499974 - CVE-2026-15718 firefox: thunderbird: Invalid pointer in the JavaScript: WebAssembly component
• BZ - 2503415 - CVE-2026-16390 firefox: thunderbird: Mitigation bypass in the Enterprise Policies component
• BZ - 2503416 - CVE-2026-16350 firefox: thunderbird: Incorrect boundary conditions in the Audio/Video: cubeb component
• BZ - 2503420 - CVE-2026-16391 firefox: thunderbird: Information disclosure in the Storage: IndexedDB component
• BZ - 2503423 - CVE-2026-16375 firefox: thunderbird: Site isolation issue in the Networking: HTTP component
• BZ - 2503425 - CVE-2026-16356 firefox: thunderbird: Sandbox escape due to use-after-free in the Disability Access APIs component
• BZ - 2503430 - CVE-2026-16363 firefox: thunderbird: JIT miscompilation in the JavaScript: WebAssembly component
• BZ - 2503432 - CVE-2026-16412 firefox: thunderbird: Memory safety bugs fixed in Firefox ESR 140.13 and Firefox 153
• BZ - 2503434 - CVE-2026-16381 firefox: thunderbird: Same-origin policy bypass in the Networking: DNS component
• BZ - 2503439 - CVE-2026-16355 firefox: thunderbird: JIT miscompilation in the JavaScript Engine: JIT component
• BZ - 2503440 - CVE-2026-16361 firefox: thunderbird: Memory safety bugs fixed in Firefox ESR 115.38 and Firefox ESR 140.13
• BZ - 2503444 - CVE-2026-16352 firefox: thunderbird: Sandbox escape due to use-after-free in the Disability Access APIs component
• BZ - 2503451 - CVE-2026-16368 firefox: thunderbird: Incorrect boundary conditions in the JavaScript: WebAssembly component
• BZ - 2503454 - CVE-2026-16377 firefox: thunderbird: Mitigation bypass in the PDF Viewer component
• BZ - 2503456 - CVE-2026-16360 firefox: thunderbird: Memory safety bugs fixed in Firefox ESR 115.38, Firefox ESR 140.13 and Firefox 153
• BZ - 2503463 - CVE-2026-16362 firefox: thunderbird: Use-after-free in the WebRTC: Audio/Video component
• BZ - 2503472 - CVE-2026-16358 firefox: thunderbird: Site isolation issue in the Graphics: WebRender component
• BZ - 2503473 - CVE-2026-16387 firefox: thunderbird: Site isolation issue in the Networking component
• BZ - 2503485 - CVE-2026-16349 firefox: thunderbird: Same-origin policy bypass in the DOM: Navigation component
• BZ - 2503489 - CVE-2026-16357 firefox: thunderbird: Incorrect boundary conditions in the Graphics component
• BZ - 2503491 - CVE-2026-16351 firefox: thunderbird: Sandbox escape due to use-after-free in the DOM: Navigation component
• BZ - 2503497 - CVE-2026-16371 firefox: thunderbird: Privilege escalation in the DOM: Navigation component
• BZ - 2503498 - CVE-2026-16379 firefox: thunderbird: Privilege escalation in the DOM: Content Processes component
• BZ - 2503500 - CVE-2026-16354 firefox: thunderbird: Information disclosure in the Graphics: ImageLib component
• BZ - 2503501 - CVE-2026-16374 firefox: thunderbird: Information disclosure in the Framework component in DevTools
• BZ - 2503505 - CVE-2026-16359 firefox: thunderbird: Incorrect boundary conditions in the Audio/Video: GMP component
• BZ - 2503512 - CVE-2026-16383 firefox: thunderbird: Mitigation bypass in the DOM: Networking component
• BZ - 2503513 - CVE-2026-16369 firefox: thunderbird: Integer overflow in the JavaScript: WebAssembly component
• BZ - 2503517 - CVE-2026-16353 firefox: thunderbird: Invalid pointer in the DOM: Bindings (WebIDL) component
• BZ - 2503521 - CVE-2026-16396 firefox: thunderbird: Privilege escalation in WebExtensions
• BZ - 2503527 - CVE-2026-16405 firefox: thunderbird: Information disclosure in the Networking: WebSockets component
• BZ - 2506217 - CVE-2026-14899 thunderbird: Off-by-one out of bounds read in MIME header parser for forwarding

CVEs

• CVE-2026-14899
• CVE-2026-15718
• CVE-2026-15719
• CVE-2026-16349
• CVE-2026-16350
• CVE-2026-16351
• CVE-2026-16352
• CVE-2026-16353
• CVE-2026-16354
• CVE-2026-16355
• CVE-2026-16356
• CVE-2026-16357
• CVE-2026-16358
• CVE-2026-16359
• CVE-2026-16360
• CVE-2026-16361
• CVE-2026-16362
• CVE-2026-16363
• CVE-2026-16368
• CVE-2026-16369
• CVE-2026-16371
• CVE-2026-16374
• CVE-2026-16375
• CVE-2026-16377
• CVE-2026-16379
• CVE-2026-16381
• CVE-2026-16383
• CVE-2026-16387
• CVE-2026-16390
• CVE-2026-16391
• CVE-2026-16396
• CVE-2026-16405
• CVE-2026-16412

References

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