RHSA-2026:38750 - 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):

• firefox: thunderbird: Sandbox escape in the DOM: Workers component (CVE-2026-12294)
• firefox: thunderbird: Information disclosure, sandbox escape in the Security: Process Sandboxing component (CVE-2026-12313)
• firefox: thunderbird: Information disclosure, sandbox escape in the Security: Process Sandboxing component (CVE-2026-12311)
• firefox: thunderbird: Memory safety bug fixed in Thunderbird ESR 140.12 (CVE-2026-12290)
• firefox: thunderbird: Memory safety bugs fixed in Firefox ESR 140.12, Thunderbird ESR 140.12, Firefox 152 and Thunderbird 152 (CVE-2026-12327)
• firefox: thunderbird: JIT miscompilation in the DOM: Core & HTML component (CVE-2026-12299)
• firefox: thunderbird: Memory safety bug fixed in Thunderbird ESR 140.12 (CVE-2026-12329)
• firefox: thunderbird: Memory safety bug fixed in Thunderbird ESR 140.12 (CVE-2026-12312)
• firefox: thunderbird: Mitigation bypass in the DOM: Security component (CVE-2026-12302)
• firefox: thunderbird: Memory safety bugs fixed in Firefox ESR 115.37, Firefox ESR 140.12, Thunderbird ESR 140.12, Firefox 152 and Thunderbird 152 (CVE-2026-12328)
• firefox: thunderbird: Incorrect boundary conditions in the Internationalization component (CVE-2026-12330)
• firefox: thunderbird: Memory safety bug fixed in Thunderbird ESR 140.12 (CVE-2026-12314)
• firefox: thunderbird: Memory safety bug fixed in Thunderbird ESR 140.12 (CVE-2026-12309)
• firefox: thunderbird: Memory safety bug fixed in Thunderbird ESR 140.12 (CVE-2026-12310)
• firefox: thunderbird: Denial-of-service in the Graphics: ImageLib component (CVE-2026-12325)
• firefox: thunderbird: Sandbox escape in the DOM: Navigation component (CVE-2026-12295)
• firefox: thunderbird: Privilege escalation in the Graphics: WebRender component (CVE-2026-12289)
• firefox: thunderbird: Mitigation bypass in the DOM: Security component (CVE-2026-12315)
• firefox: thunderbird: Sandbox escape in the Security: Process Sandboxing component (CVE-2026-12296)
• firefox: thunderbird: Memory safety bug fixed in Thunderbird ESR 140.12 (CVE-2026-12306)
• firefox: thunderbird: Memory safety bug fixed in Thunderbird ESR 140.12 (CVE-2026-12307)
• firefox: thunderbird: Sandbox escape due to incorrect boundary conditions in the Networking component (CVE-2026-12297)
• firefox: thunderbird: Memory safety bug fixed in Thunderbird ESR 140.12 (CVE-2026-12305)
• firefox: thunderbird: Incorrect boundary conditions in the Web Audio component (CVE-2026-12292)
• firefox: thunderbird: Memory safety bug fixed in Thunderbird ESR 140.12 (CVE-2026-12308)
• firefox: thunderbird: Incorrect boundary conditions in the Graphics: CanvasWebGL component (CVE-2026-12324)
• firefox: thunderbird: Same-origin policy bypass in the Networking: Cookies component (CVE-2026-12304)
• firefox: thunderbird: Use-after-free in the Networking: HTTP component (CVE-2026-12291)
• firefox: thunderbird: Memory safety bug fixed in Firefox ESR 140.12 (CVE-2026-12298)

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 - 2489207 - CVE-2026-12294 firefox: thunderbird: Sandbox escape in the DOM: Workers component
• BZ - 2489208 - CVE-2026-12313 firefox: thunderbird: Information disclosure, sandbox escape in the Security: Process Sandboxing component
• BZ - 2489209 - CVE-2026-12311 firefox: thunderbird: Information disclosure, sandbox escape in the Security: Process Sandboxing component
• BZ - 2489210 - CVE-2026-12290 firefox: thunderbird: Memory safety bug fixed in Thunderbird ESR 140.12
• BZ - 2489211 - CVE-2026-12327 firefox: thunderbird: Memory safety bugs fixed in Firefox ESR 140.12, Thunderbird ESR 140.12, Firefox 152 and Thunderbird 152
• BZ - 2489212 - CVE-2026-12299 firefox: thunderbird: JIT miscompilation in the DOM: Core & HTML component
• BZ - 2489214 - CVE-2026-12329 firefox: thunderbird: Memory safety bug fixed in Thunderbird ESR 140.12
• BZ - 2489215 - CVE-2026-12312 firefox: thunderbird: Memory safety bug fixed in Thunderbird ESR 140.12
• BZ - 2489217 - CVE-2026-12302 firefox: thunderbird: Mitigation bypass in the DOM: Security component
• BZ - 2489218 - CVE-2026-12328 firefox: thunderbird: Memory safety bugs fixed in Firefox ESR 115.37, Firefox ESR 140.12, Thunderbird ESR 140.12, Firefox 152 and Thunderbird 152
• BZ - 2489220 - CVE-2026-12330 firefox: thunderbird: Incorrect boundary conditions in the Internationalization component
• BZ - 2489221 - CVE-2026-12314 firefox: thunderbird: Memory safety bug fixed in Thunderbird ESR 140.12
• BZ - 2489223 - CVE-2026-12309 firefox: thunderbird: Memory safety bug fixed in Thunderbird ESR 140.12
• BZ - 2489224 - CVE-2026-12310 firefox: thunderbird: Memory safety bug fixed in Thunderbird ESR 140.12
• BZ - 2489225 - CVE-2026-12325 firefox: thunderbird: Denial-of-service in the Graphics: ImageLib component
• BZ - 2489226 - CVE-2026-12295 firefox: thunderbird: Sandbox escape in the DOM: Navigation component
• BZ - 2489229 - CVE-2026-12289 firefox: thunderbird: Privilege escalation in the Graphics: WebRender component
• BZ - 2489231 - CVE-2026-12315 firefox: thunderbird: Mitigation bypass in the DOM: Security component
• BZ - 2489232 - CVE-2026-12296 firefox: thunderbird: Sandbox escape in the Security: Process Sandboxing component
• BZ - 2489233 - CVE-2026-12306 firefox: thunderbird: Memory safety bug fixed in Thunderbird ESR 140.12
• BZ - 2489234 - CVE-2026-12307 firefox: thunderbird: Memory safety bug fixed in Thunderbird ESR 140.12
• BZ - 2489235 - CVE-2026-12297 firefox: thunderbird: Sandbox escape due to incorrect boundary conditions in the Networking component
• BZ - 2489236 - CVE-2026-12305 firefox: thunderbird: Memory safety bug fixed in Thunderbird ESR 140.12
• BZ - 2489237 - CVE-2026-12292 firefox: thunderbird: Incorrect boundary conditions in the Web Audio component
• BZ - 2489239 - CVE-2026-12308 firefox: thunderbird: Memory safety bug fixed in Thunderbird ESR 140.12
• BZ - 2489240 - CVE-2026-12324 firefox: thunderbird: Incorrect boundary conditions in the Graphics: CanvasWebGL component
• BZ - 2489243 - CVE-2026-12304 firefox: thunderbird: Same-origin policy bypass in the Networking: Cookies component
• BZ - 2489244 - CVE-2026-12291 firefox: thunderbird: Use-after-free in the Networking: HTTP component
• BZ - 2489248 - CVE-2026-12298 firefox: thunderbird: Memory safety bug fixed in Firefox ESR 140.12

CVEs

• CVE-2026-12289
• CVE-2026-12290
• CVE-2026-12291
• CVE-2026-12292
• CVE-2026-12294
• CVE-2026-12295
• CVE-2026-12296
• CVE-2026-12297
• CVE-2026-12298
• CVE-2026-12299
• CVE-2026-12302
• CVE-2026-12304
• CVE-2026-12305
• CVE-2026-12306
• CVE-2026-12307
• CVE-2026-12308
• CVE-2026-12309
• CVE-2026-12310
• CVE-2026-12311
• CVE-2026-12312
• CVE-2026-12313
• CVE-2026-12314
• CVE-2026-12315
• CVE-2026-12324
• CVE-2026-12325
• CVE-2026-12327
• CVE-2026-12328
• CVE-2026-12329
• CVE-2026-12330

References

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