CVE-2026-117896

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 (2026-11-02) --- 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 ensure proper object lifetime management in the DOM: Core & HTML component to eliminate use-after-free conditions during HTML parsing: upgrade to Firefox 159, Firefox ESR 115.44, and Firefox ESR 153.6 (or the fixed Firefox/Rhel10/Firefox Flatpak builds), which corrects memory handling in the DOM: Core & HTML component to prevent access to freed memory objects during document rendering, closing all 2 injection vectors (crafted web page, malicious HTML document). Until patched, this is a concern on client systems rendering untrusted web content or HTML files in affected browser sessions, so restrict user navigation to untrusted websites and avoid opening untrusted HTML documents in affected browser sessions. As a compensating measure, Enable ASLR to randomize browser address space layout and hinder reliable code execution, Enforce full RELRO and PIE to maintain position-independent executable layout and read-only relocation structures against code-reuse attacks, and Run SELinux in enforcing mode to confine the Firefox process to its designated domain and block unauthorized host access. 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)