CVE-2026-117930

A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the following issue: Use-after-free in the DOM: Bindings (WebIDL) 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 reference tracking in the DOM WebIDL binding component to eliminate use-after-free conditions: upgrade to Firefox 159, Firefox ESR 115.44, Firefox ESR 153.6 (or the fixed Firefox/Rhel10/Firefox Flatpak builds), which corrects object lifecycle management in the DOM WebIDL binding component to prevent use-after-free conditions, closing all 2 injection vectors (crafted web page, malicious DOM WebIDL script execution). Until patched, this is a concern on deployments where users visit untrusted websites or render untrusted HTML content in Firefox or Thunderbird, so restrict browsing to trusted web content and avoid rendering untrusted HTML in affected browser or email client sessions. As a compensating measure, maintain ASLR to randomize the browser process address space and hinder pointer hijacking, utilize full RELRO and PIE to protect the Global Offset Table and impede control-flow hijacking, and run SELinux in enforcing mode to confine the browser process and restrict unauthorized system access. These controls limit blast radius and contain exploitation, but they do not fix the underlying DOM WebIDL use-after-free defect — apply the upstream patch to fully remediate.

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