RHSA-2026:53455: Important: thunderbird security update

Published Aug 11, 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

2 affected components
Red Hat Red Hat Enterprise Linux for x86_64 - Extended Life Cycle Long Life
Red Hat Red Hat Enterprise Linux Server - AUS

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

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

    Fixed in 115.38
  2. Upgrade

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

    Fixed in 140.13
  3. Upgrade

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

    Fixed in 153
  4. Upgrade

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

    Patch CVE-2026-16359
  5. Upgrade

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

    Patch CVE-2026-16350
  6. Upgrade

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

    Patch CVE-2026-16357
  7. Upgrade

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

    Patch CVE-2026-16368
  8. Upgrade

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

    Patch CVE-2026-16374
  9. Upgrade

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

    Patch CVE-2026-16354
  10. Upgrade

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

    Patch CVE-2026-16405
  11. Upgrade

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

    Patch CVE-2026-16391
  12. Upgrade

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

    Patch CVE-2026-16369
  13. Upgrade

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

    Patch CVE-2026-16353
  14. Upgrade

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

    Patch CVE-2026-15718
  15. Upgrade

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

    Patch CVE-2026-16355
  16. Upgrade

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

    Patch CVE-2026-16363
  17. Upgrade

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

    Patch CVE-2026-16360
  18. Upgrade

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

    Patch CVE-2026-16412
  19. Upgrade

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

    Patch CVE-2026-16361
  20. Upgrade

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

    Patch CVE-2026-16383
  21. Upgrade

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

    Patch CVE-2026-16390
  22. Upgrade

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

    Patch CVE-2026-16377
  23. Upgrade

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

    Patch CVE-2026-16396
  24. Upgrade

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

    Patch CVE-2026-16379
  25. Upgrade

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

    Patch CVE-2026-16371
  26. Upgrade

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

    Patch CVE-2026-16349
  27. Upgrade

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

    Patch CVE-2026-16381
  28. Upgrade

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

    Patch CVE-2026-16351
  29. Upgrade

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

    Patch CVE-2026-16352
  30. Upgrade

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

    Patch CVE-2026-16356
  31. Upgrade

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

    Patch CVE-2026-16358
  32. Upgrade

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

    Patch CVE-2026-16387
  33. Upgrade

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

    Patch CVE-2026-16375
  34. Upgrade

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

    Patch CVE-2026-16362
  35. Upgrade

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

    Patch CVE-2026-14899
  36. Upgrade

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

    Patch CVE-2026-15719

Event History

Aug 11, 2026
Advisory Published
via Red Hat·12:00 AM
Data Sourced
via Red Hat·12:00 AM
RemedyDescriptionAffected Software
Advisory Published
via Red Hat·12:10 PM
Data Sourced
via Red Hat·12:10 PM
Severity
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Frequently Asked Questions

1

What is the severity of RHSA-2026:53455?

The severity of RHSA-2026:53455 is categorized as high with a score of 7.

2

What security issues are addressed in RHSA-2026:53455?

RHSA-2026:53455 addresses a site isolation issue in the DOM and an invalid pointer in the JavaScript: WebAssembly component.

3

How do I fix RHSA-2026:53455?

To fix RHSA-2026:53455, update your Mozilla Thunderbird installation to the latest version provided in the security update.

4

What vulnerabilities are associated with RHSA-2026:53455?

RHSA-2026:53455 is associated with vulnerabilities including an integer overflow and a use after free.

5

Who is affected by RHSA-2026:53455?

RHSA-2026:53455 affects users of Red Hat Enterprise Linux systems running the Mozilla Thunderbird email client.

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