CVE-2026-117936

A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the following issue: Use-after-free in the DOM: Core & HTML component

Red Hat Product Security rates the severity of this flaw as determined by the Mozilla Foundation Security Advisory.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

--- CME Mitigation Guidance (2026-11-03) --- Disclaimer: The following mitigation solutions are provided as a courtesy, pending the application of an official patch. This content was generated utilizing AI tools in conjunction with data from https://cmetaxonomy.org. Customers are advised to independently evaluate and test these temporary mitigations within their own infrastructure.

The highest-value action is to correct object lifecycle and memory management in the DOM Core & HTML component of Firefox and Thunderbird to eliminate use-after-free conditions: upgrade to Firefox 159, Firefox ESR 115.44, and Firefox ESR 153.6 (or the corresponding fixed Red Hat builds), which remediates the use-after-free condition in the DOM: Core & HTML component, closing all 2 injection vectors (crafted web page, crafted HTML document). Until patched, this is a concern on Users opening web content or HTML documents in affected Firefox and Thunderbird installations across all supported platforms, so Prevent or restrict users from navigating to untrusted web pages or opening untrusted HTML documents in vulnerable browser instances. As a compensating measure, Enable Address Space Layout Randomization to randomize the browser memory layout and obstruct reliable exploitation, Utilize full RELRO and PIE to enforce position-independent executable code and read-only relocations, and Maintain SELinux in enforcing mode to restrict the browser process within least-privilege mandatory access control boundaries. These controls limit blast radius and contain exploitation, but they do not fix the underlying use-after-free defect — apply the upstream patch to fully remediate.

Highest-impact CME: CME-301 SELinux (Enforcing Mode) (medium)