CVE-2026-117878

A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the following issue: Other issue, use-after-free in the Storage: IndexedDB 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 prevent use-after-free memory corruption in the Storage: IndexedDB component during storage lifecycle handling: upgrade to Firefox 159, Firefox ESR 115.44, and Firefox ESR 153.6 (or the corresponding fixed Red Hat builds), which resolves the use-after-free memory corruption defect within the Storage: IndexedDB component, closing crafted web page invoking IndexedDB API calls. Until patched, this is a concern on Firefox and Thunderbird users loading web content across all supported platforms, so restrict users from navigating to untrusted websites or loading untrusted web content capable of invoking IndexedDB API calls. As a compensating measure, enable Address Space Layout Randomization to randomize browser memory layout and hinder reliable exploitation and disable or strictly sandbox client-side JavaScript to prevent untrusted content from executing IndexedDB API calls. These controls limit blast radius and contain exploitation, but they do not fix the underlying use-after-free defect in Storage: IndexedDB — apply the upstream patch to fully remediate.

Highest-impact CME: CME-1309 Script Engine Restriction (Sandbox / Disable) (medium)