CVE-2026-117880

A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the following issue: Use-after-free in the XML 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 prevent the application from parsing untrusted XML content and restrict loading untrusted web pages in affected browser instances: upgrade to Firefox 159, Firefox ESR 115.44, and Firefox ESR 153.6 (or the corresponding fixed Red Hat builds), which resolves a use-after-free memory corruption condition in the XML processing component, closing all 2 injection vectors (crafted XML document, malicious web page). Until patched, this is a concern on Any deployment running Firefox or Thunderbird parsing untrusted XML documents or loading external web pages, so Restrict users from opening untrusted web links and parsing untrusted or external XML documents. As a compensating measure, Ensure Address Space Layout Randomization (ASLR) is enforced across the userspace environment to obstruct reliable code execution. 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-101 ASLR (Address Space Layout Randomization) (medium)