CVE-2026-117951

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 isolate untrusted DOM manipulation scripts and restrict rendering of untrusted HTML within the DOM: Core & HTML component: upgrade to Firefox 159, Firefox ESR 115.44, Firefox ESR 153.6 (or the corresponding fixed Red Hat builds), which remediates the use-after-free memory corruption condition within the DOM: Core & HTML component, closing all 2 injection vectors (malicious HTML document, crafted DOM manipulation script). Until patched, this is a concern on Firefox installations processing untrusted web pages or HTML content across all supported platforms, so Restrict users from opening untrusted HTML documents or navigating to untrusted websites in affected browser instances. As a compensating measure, Maintain Address Space Layout Randomization (ASLR) to randomize userspace memory layout and impede reliable shellcode or ROP execution, Enforce Full RELRO and PIE to ensure a read-only Global Offset Table and position-independent execution, hindering memory redirection, and Run SELinux in Enforcing mode to confine the Firefox process domain and restrict access to unauthorized files, network resources, and system interfaces. 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)