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Firefox Security Update — AlmaLinux 8 (ALSA-2026:76850)

ALSA-2026:76850 is a Critical-rated Firefox security update for AlmaLinux 8 (aggregate CVSS 9.6, buffer-class CWE-119) fixing a large batch of Mozilla vulnerabilities — including a sandbox escape via incorrect boundary conditions in the Graphics component (CVE-2026-92035), use-after-free flaws in Canvas2D and the Layout text/fonts component (CVE-2026-100832, CVE-2026-100784), and a DLL-Service privilege escalation. Servers with Firefox installed for testing or automation should update it: dnf update firefox.

Critical 9.6 CVSS
AlmaLinux 8

Was das unter einer SharedLicense-Lizenz bedeutet

Firefox batches like this chain: sandbox escape plus memory-corruption flaws in the same release means a single malicious page can go from rendering to code execution — relevant on any server or admin workstation running a browser.

Mozilla Firefox is an open-source web browser, designed for standards compliance, performance, and portability.  

Security Fix(es):  

  * firefox: thunderbird: Sandbox escape due to incorrect boundary conditions in the Graphics component (CVE-2026-92035)
  * firefox: thunderbird: Use-after-free in the Graphics: Canvas2D component (CVE-2026-100832)
  * firefox: Use-after-free in the Layout: Text and Fonts component (CVE-2026-100784)
  * firefox: thunderbird: Privilege escalation in the DLL Services component (CVE-2026-100801)
  * firefox: thunderbird: Sandbox escape due to incorrect boundary conditions in the Internationalization component (CVE-2026-100794)
  * firefox: thunderbird: Privilege escalation in the Address Bar component (CVE-2026-100820)
  * firefox: thunderbird: Use-after-free in the Graphics: Canvas2D component (CVE-2026-100777)
  * firefox: thunderbird: Information disclosure in the Networking: JAR component (CVE-2026-100766)
  * firefox: thunderbird: Use-after-free in the XSLT component (CVE-2026-100779)
  * firefox: thunderbird: Privilege escalation in the DOM: Service Workers component (CVE-2026-100807)
  * firefox: thunderbird: JIT miscompilation in the JavaScript: WebAssembly component (CVE-2026-100792)
  * firefox: Privilege escalation due to use-after-free in the Graphics: WebRender component (CVE-2026-100797)
  * firefox: thunderbird: Sandbox escape due to incorrect boundary conditions in the XPCOM component (CVE-2026-100819)
  * firefox: thunderbird: Use-after-free in the JavaScript: WebAssembly component (CVE-2026-100776)
  * firefox: thunderbird: Use-after-free in the Widget component (CVE-2026-100757)
  * firefox: Sandbox escape due to use-after-free in the Graphics component (CVE-2026-100786)
  * firefox: thunderbird: Information disclosure in the Networking component (CVE-2026-96869)
  * firefox: Sandbox escape due to use-after-free in the DOM: Content Processes component (CVE-2026-100770)
  * firefox: thunderbird: Use-after-free in the JavaScript: WebAssembly component (CVE-2026-100769)
  * firefox: Use-after-free in the DOM: Core & HTML component (CVE-2026-100791)
  * firefox: thunderbird: Sandbox escape due to use-after-free in the Widget: Gtk component (CVE-2026-100818)
  * firefox: thunderbird: Privilege escalation due to incorrect boundary conditions in the Graphics component (CVE-2026-100782)
  * firefox: firefox: Sandbox escape via use-after-free in DOM component (CVE-2026-100811)
  * firefox: thunderbird: Use-after-free in the DOM: Core & HTML component (CVE-2026-100772)
  * firefox: thunderbird: Uninitialized memory in the Storage: Quota Manager component (CVE-2026-100759)
  * firefox: Sandbox escape due to use-after-free in the DOM: Core & HTML component (CVE-2026-100778)
  * firefox: thunderbird: Sandbox escape in the DOM: Navigation component (CVE-2026-100758)
  * firefox: thunderbird: Sandbox escape in the Graphics component (CVE-2026-100775)
  * firefox: thunderbird: Sandbox escape due to incorrect boundary conditions in the Graphics: WebRender component (CVE-2026-100781)
  * firefox: Use-after-free in the DOM: Core & HTML component (CVE-2026-100774)
  * firefox: thunderbird: Same-origin policy bypass in the WebExtensions component (CVE-2026-100803)
  * firefox: thunderbird: Use-after-free in the Graphics: Canvas2D component (CVE-2026-100789)
  * firefox: thunderbird: Use-after-free in the DOM: Core & HTML component (CVE-2026-100785)
  * firefox: thunderbird: Site isolation issue in the Panning and Zooming component (CVE-2026-100821)
  * firefox: thunderbird: Invalid pointer in the JavaScript: WebAssembly component (CVE-2026-100788)
  * firefox: thunderbird: Undefined behavior in the DOM: Streams component (CVE-2026-100771)
  * firefox: Sandbox escape due to use-after-free in the DOM: Content Processes component (CVE-2026-100762)
  * firefox: thunderbird: Use-after-free in the XSLT component (CVE-2026-100790)
  * firefox: thunderbird: Use-after-free in the Storage: IndexedDB component (CVE-2026-100773)
  * firefox: thunderbird: Use-after-free in the DOM: Core & HTML component (CVE-2026-100780)
  * firefox: thunderbird: Use-after-free in the Networking: Cache component (CVE-2026-100767)
  * firefox: thunderbird: Incorrect boundary conditions in the Audio/Video: Playback component (CVE-2026-100756)
  * firefox: thunderbird: Uninitialized memory in the Audio/Video component (CVE-2026-100783)


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.

Häufig gestellte Fragen

What is ALSA-2026:76850?
It is AlmaLinux's Critical-rated Firefox erratum for AlmaLinux 8 (aggregate CVSS 9.6, CWE-119 buffer-condition class). It fixes dozens of Mozilla vulnerabilities, headlined by a Graphics-component sandbox escape (CVE-2026-92035), use-after-free flaws in Canvas2D (CVE-2026-100832) and Layout text/fonts (CVE-2026-100784), and a DLL-Service privilege escalation — the same fixes shipped to Thunderbird where noted.
Do servers need Firefox at all?
Usually not — but servers that run browser-based testing, screenshots or admin tooling do have it installed. If your servers do not need Firefox, removing it is the cleanest security posture; if they do, dnf update firefox applies this erratum.
How do I update Firefox on AlmaLinux 8?
Run dnf update firefox and relaunch any running Firefox instance — the browser loads the patched binary on next start. Verify with firefox --version after updating.
Why do so many CVEs appear in one Firefox advisory?
Mozilla ships its fixes in consolidated releases, and AlmaLinux repackages them per architecture — so one erratum carries the whole batch (43 CVEs in this case). The volume is normal for Firefox; the sandbox escape in this batch is what raises the rating to Critical.

Referenzen

Sicherheitshinweise

Verwandte Warnhinweise

Qt5-Qtdeclarative Security Update — AlmaLinux 8 (ALSA-2026:96075)

2026-11-10

Webkit2gtk3 Security Update — AlmaLinux 8 (ALSA-2026:96080)

2026-11-09

Util-Linux Security Update — AlmaLinux 8 (ALSA-2026:96212)

2026-11-09

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