CVE-2026-117898

A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the following issue: Use-after-free in the JavaScript Engine: JIT 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 disable or restrict the JIT compiler via browser configuration to eliminate the vulnerable JIT compilation engine directly: upgrade to Firefox 159, Firefox ESR 153.6, and Thunderbird 159 (or the corresponding fixed Red Hat builds), which fixes a use-after-free vulnerability in the JavaScript Engine JIT component, closing all 2 injection vectors (malicious web page execution, crafted JavaScript execution). Until patched, this is a concern on systems running Firefox or Thunderbird where users visit untrusted web pages or execute untrusted JavaScript, so prevent users from visiting untrusted websites or executing untrusted JavaScript in the browser. As a compensating measure, ensure Address Space Layout Randomization is active to make reliable code execution via memory corruption harder. 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-919 JIT Compiler Hardening (JIT Restriction / V8 Sandbox) (high)