RHSA-2026:54259: Important: firefox security update

Published Aug 12, 2026
·
Updated

Important: firefox security update

Other sources

Mozilla Firefox is an open-source web browser, designed for standards compliance, performance, and portability.Security Fix(es): libaom: libaom: heap buffer overflow in AV1 encoder first-pass stats buffer via LAP mode (CVE-2026-56208) 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) 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

6 affected componentsFixes available
Red Hat Red Hat Enterprise Linux for x86_64 - Extended Life Cycle Long Life
Red Hat Red Hat Enterprise Linux Server - AUS
redhat/firefox<140.13.0-1.el8_6
140.13.0-1.el8_6
redhat/firefox<140.13.0-1.el8_6
140.13.0-1.el8_6
redhat/firefox-debuginfo<140.13.0-1.el8_6
140.13.0-1.el8_6
redhat/firefox-debugsource<140.13.0-1.el8_6
140.13.0-1.el8_6

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

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

    Fixed in 140.13.0-1.el8_6
  2. Upgrade

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

    Fixed in 140.13.0-1.el8_6
  3. Upgrade

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

    Fixed in 140.13.0-1.el8_6
  4. Upgrade

    Upgrade Mozilla Firefox / Firefox ESR 115.38 to a version that resolves this vulnerability.

    Fixed in 115.38
  5. Upgrade

    Upgrade Mozilla Firefox ESR 140.13 to a version that resolves this vulnerability.

    Fixed in 140.13
  6. Upgrade

    Upgrade Mozilla Firefox 153 to a version that resolves this vulnerability.

    Fixed in 153
  7. Upgrade

    Upgrade Mozilla Firefox / libaom to a version that resolves this vulnerability.

    Patch CVE-2026-56208

Event History

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

1

What is the severity of RHSA-2026:54259?

The severity of RHSA-2026:54259 is rated as high with a score of 7.

2

How do I fix RHSA-2026:54259?

To fix RHSA-2026:54259, update the Mozilla Firefox package to the latest version as provided by Red Hat.

3

What vulnerabilities are addressed in RHSA-2026:54259?

RHSA-2026:54259 addresses a heap buffer overflow vulnerability in the AV1 encoder as well as other security issues.

4

What systems are affected by RHSA-2026:54259?

RHSA-2026:54259 affects Red Hat Enterprise Linux for x86_64 and the redhat/firefox packages.

5

Is RHSA-2026:54259 a critical update?

Yes, RHSA-2026:54259 is considered an important security update that should be applied promptly.

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