RHSA-2026:54248: 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

9 affected componentsFixes available
Red Hat Red Hat Enterprise Linux Server - Extended Life Cycle Support for IBM Power, big endian
Red Hat Red Hat Enterprise Linux Server - Extended Life Cycle Support for IBM Power, little endian
Red Hat Red Hat Enterprise Linux Server - Extended Life Cycle Support (for IBM z Systems)
Red Hat Red Hat Enterprise Linux Server - Extended Life Cycle Support
redhat/firefox<140.13.0-1.el7_9
140.13.0-1.el7_9
redhat/firefox<140.13.0-1.el7_9
140.13.0-1.el7_9
redhat/firefox-debuginfo<140.13.0-1.el7_9
140.13.0-1.el7_9
redhat/firefox<140.13.0-1.el7_9
140.13.0-1.el7_9
redhat/firefox-debuginfo<140.13.0-1.el7_9
140.13.0-1.el7_9

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.el7_9
  2. Upgrade

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

    Fixed in 140.13.0-1.el7_9
  3. Upgrade

    Upgrade firefox ESR 115 to a version that resolves this vulnerability.

    Fixed in 115.38
  4. Upgrade

    Upgrade firefox ESR 140 to a version that resolves this vulnerability.

    Fixed in 140.13
  5. Upgrade

    Upgrade firefox to a version that resolves this vulnerability.

    Fixed in 153
  6. Upgrade

    Upgrade 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·08:50 AM
Data Sourced
via Red Hat·08:50 AM
Severity
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Frequently Asked Questions

1

What is the severity of RHSA-2026:54248?

The severity of RHSA-2026:54248 is high with a score of 7.

2

How do I fix RHSA-2026:54248?

To fix RHSA-2026:54248, update your Mozilla Firefox packages to the latest version available.

3

What security vulnerabilities does RHSA-2026:54248 address?

RHSA-2026:54248 addresses a heap buffer overflow in the AV1 encoder and other related issues within Firefox and Thunderbird.

4

Which software is affected by RHSA-2026:54248?

RHSA-2026:54248 affects Red Hat Firefox and Red Hat Firefox debuginfo packages.

5

When was RHSA-2026:54248 published?

RHSA-2026:54248 was published on August 12, 2026.

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