RHSA-2026:49921: Important: thunderbird security update

Published Aug 4, 2026
·
Updated

Important: thunderbird security update

Other sources

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.

— Red Hat

Affected Software

28 affected componentsFixes available
Red Hat Red Hat Enterprise Linux for IBM z Systems - Extended Update Support
Red Hat Red Hat Enterprise Linux for Power, little endian
Red Hat Red Hat Enterprise Linux for x86_64 - Extended Life Cycle
Red Hat Red Hat Enterprise Linux for Power, little endian - Extended Life Cycle
Red Hat Red Hat Enterprise Linux for ARM 64 - 4 years of updates
Red Hat Red Hat Enterprise Linux for IBM z Systems
Red Hat Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions
Red Hat Red Hat Enterprise Linux for IBM z Systems - 4 years of updates
Red Hat Red Hat Enterprise Linux for x86_64
Red Hat Red Hat Enterprise Linux for ARM 64 - Extended Update Support
Red Hat Red Hat Enterprise Linux for IBM z Systems - Extended Life Cycle
Red Hat Red Hat Enterprise Linux for ARM 64 - Extended Life Cycle
Red Hat Red Hat Enterprise Linux for ARM 64
Red Hat Red Hat Enterprise Linux for x86_64 - Extended Update Support
Red Hat Red Hat Enterprise Linux for Power, little endian - Extended Update Support
Red Hat Red Hat Enterprise Linux Server for Power LE - Update Services for SAP Solutions
redhat/thunderbird<140.13.0-1.el9_8
140.13.0-1.el9_8
redhat/thunderbird<140.13.0-1.el9_8
140.13.0-1.el9_8
redhat/thunderbird-debuginfo<140.13.0-1.el9_8
140.13.0-1.el9_8
redhat/thunderbird-debugsource<140.13.0-1.el9_8
140.13.0-1.el9_8
redhat/thunderbird-debuginfo<140.13.0-1.el9_8
140.13.0-1.el9_8
redhat/thunderbird-debugsource<140.13.0-1.el9_8
140.13.0-1.el9_8
redhat/thunderbird<140.13.0-1.el9_8
140.13.0-1.el9_8
redhat/thunderbird-debuginfo<140.13.0-1.el9_8
140.13.0-1.el9_8
redhat/thunderbird-debugsource<140.13.0-1.el9_8
140.13.0-1.el9_8
redhat/thunderbird<140.13.0-1.el9_8.aa
140.13.0-1.el9_8.aa
redhat/thunderbird-debuginfo<140.13.0-1.el9_8.aa
140.13.0-1.el9_8.aa
redhat/thunderbird-debugsource<140.13.0-1.el9_8.aa
140.13.0-1.el9_8.aa

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade redhat/thunderbird to a version that resolves this vulnerability.

    Fixed in 140.13.0-1.el9_8
  2. Upgrade

    Upgrade redhat/thunderbird-debuginfo to a version that resolves this vulnerability.

    Fixed in 140.13.0-1.el9_8
  3. Upgrade

    Upgrade redhat/thunderbird-debugsource to a version that resolves this vulnerability.

    Fixed in 140.13.0-1.el9_8
  4. Upgrade

    Upgrade redhat/thunderbird to a version that resolves this vulnerability.

    Fixed in 140.13.0-1.el9_8.aa
  5. Upgrade

    Upgrade redhat/thunderbird-debuginfo to a version that resolves this vulnerability.

    Fixed in 140.13.0-1.el9_8.aa
  6. Upgrade

    Upgrade redhat/thunderbird-debugsource to a version that resolves this vulnerability.

    Fixed in 140.13.0-1.el9_8.aa
  7. Upgrade

    Upgrade firefox/thunderbird to a version that resolves this vulnerability.

    Patch CVE-2026-16359
  8. Upgrade

    Upgrade firefox/thunderbird to a version that resolves this vulnerability.

    Patch CVE-2026-16350
  9. Upgrade

    Upgrade firefox/thunderbird to a version that resolves this vulnerability.

    Patch CVE-2026-16357
  10. Upgrade

    Upgrade firefox/thunderbird to a version that resolves this vulnerability.

    Patch CVE-2026-16368
  11. Upgrade

    Upgrade firefox/thunderbird to a version that resolves this vulnerability.

    Patch CVE-2026-16374
  12. Upgrade

    Upgrade firefox/thunderbird to a version that resolves this vulnerability.

    Patch CVE-2026-16354
  13. Upgrade

    Upgrade firefox/thunderbird to a version that resolves this vulnerability.

    Patch CVE-2026-16405
  14. Upgrade

    Upgrade firefox/thunderbird to a version that resolves this vulnerability.

    Patch CVE-2026-16391
  15. Upgrade

    Upgrade firefox/thunderbird to a version that resolves this vulnerability.

    Patch CVE-2026-16369
  16. Upgrade

    Upgrade firefox/thunderbird to a version that resolves this vulnerability.

    Patch CVE-2026-16353
  17. Upgrade

    Upgrade firefox/thunderbird to a version that resolves this vulnerability.

    Patch CVE-2026-15718
  18. Upgrade

    Upgrade firefox/thunderbird to a version that resolves this vulnerability.

    Patch CVE-2026-16355
  19. Upgrade

    Upgrade firefox/thunderbird to a version that resolves this vulnerability.

    Patch CVE-2026-16363
  20. Upgrade

    Upgrade firefox/thunderbird to a version that resolves this vulnerability.

    Fixed in 115.38
  21. Upgrade

    Upgrade firefox/thunderbird to a version that resolves this vulnerability.

    Fixed in 140.13
  22. Upgrade

    Upgrade firefox/thunderbird to a version that resolves this vulnerability.

    Patch CVE-2026-16361
  23. Upgrade

    Upgrade firefox/thunderbird to a version that resolves this vulnerability.

    Fixed in 153
  24. Upgrade

    Upgrade firefox/thunderbird to a version that resolves this vulnerability.

    Patch CVE-2026-16360
  25. Upgrade

    Upgrade firefox/thunderbird to a version that resolves this vulnerability.

    Patch CVE-2026-16412
  26. Upgrade

    Upgrade firefox/thunderbird to a version that resolves this vulnerability.

    Patch CVE-2026-16383
  27. Upgrade

    Upgrade firefox/thunderbird to a version that resolves this vulnerability.

    Patch CVE-2026-16390
  28. Upgrade

    Upgrade firefox/thunderbird to a version that resolves this vulnerability.

    Patch CVE-2026-16377
  29. Upgrade

    Upgrade firefox/thunderbird to a version that resolves this vulnerability.

    Patch CVE-2026-16396
  30. Upgrade

    Upgrade firefox/thunderbird to a version that resolves this vulnerability.

    Patch CVE-2026-16379
  31. Upgrade

    Upgrade firefox/thunderbird to a version that resolves this vulnerability.

    Patch CVE-2026-16371
  32. Upgrade

    Upgrade firefox/thunderbird to a version that resolves this vulnerability.

    Patch CVE-2026-16349
  33. Upgrade

    Upgrade firefox/thunderbird to a version that resolves this vulnerability.

    Patch CVE-2026-16381
  34. Upgrade

    Upgrade firefox/thunderbird to a version that resolves this vulnerability.

    Patch CVE-2026-16351
  35. Upgrade

    Upgrade firefox/thunderbird to a version that resolves this vulnerability.

    Patch CVE-2026-16352
  36. Upgrade

    Upgrade firefox/thunderbird to a version that resolves this vulnerability.

    Patch CVE-2026-16356
  37. Upgrade

    Upgrade firefox/thunderbird to a version that resolves this vulnerability.

    Patch CVE-2026-16358
  38. Upgrade

    Upgrade firefox/thunderbird to a version that resolves this vulnerability.

    Patch CVE-2026-16387
  39. Upgrade

    Upgrade firefox/thunderbird to a version that resolves this vulnerability.

    Patch CVE-2026-16375
  40. Upgrade

    Upgrade firefox/thunderbird to a version that resolves this vulnerability.

    Patch CVE-2026-16362
  41. Upgrade

    Upgrade firefox/thunderbird to a version that resolves this vulnerability.

    Patch CVE-2026-14899
  42. Upgrade

    Upgrade firefox/thunderbird to a version that resolves this vulnerability.

    Patch CVE-2026-15719

Event History

Aug 4, 2026
Advisory Published
via Red Hat·12:00 AM
Data Sourced
via Red Hat·12:00 AM
RemedyDescriptionAffected Software
Advisory Published
via Red Hat·07:09 AM
Data Sourced
via Red Hat·07:09 AM
Severity
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Frequently Asked Questions

1

What is the severity of RHSA-2026:49921?

The severity of RHSA-2026:49921 is classified as high, with a score of 7.

2

What vulnerabilities are addressed in RHSA-2026:49921?

RHSA-2026:49921 addresses a site isolation issue in the DOM and an invalid pointer in the JavaScript WebAssembly component.

3

How do I fix RHSA-2026:49921?

To fix RHSA-2026:49921, users should apply the latest security updates for Mozilla Thunderbird from Red Hat.

4

What software is affected by RHSA-2026:49921?

Affected software includes Red Hat Thunderbird, Red Hat Thunderbird debuginfo, and Red Hat Thunderbird debugsource across various Red Hat Enterprise Linux platforms.

5

Is the RHSA-2026:49921 update critical for users?

Yes, RHSA-2026:49921 is important as it addresses significant security vulnerabilities that could impact user security.

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