CVE-2026-84117: Vulnerability in Mozilla Firefox

CVE-2026-84117 and related CVEs represent a collection of security vulnerabilities fixed in Mozilla Firefox 155. These include privilege escalation, use-after-free bugs in various components such as JavaScript GC, DOM navigation, Audio/Video, Graphics WebGPU, and sandbox escapes. Some issues also involve information disclosure and site isolation weaknesses. The bugs were discovered internally and externally, with some showing evidence of memory corruption or other security-relevant defects that could potentially be exploited. The Mozilla advisory MFSA 2026-82 confirms these fixes and provides detailed references for each issue.

The vulnerabilities have a high impact rating (CVSS 8.8) with potential for privilege escalation, information disclosure, sandbox escapes, and denial of service. Exploitation could lead to complete compromise of the affected Firefox environment, including elevated privileges and bypassing security boundaries. No known exploits in the wild have been reported at the time of the advisory.

Mozilla has released Firefox 155 which includes fixes for all these vulnerabilities. Users and administrators should update to Firefox 155 or later to mitigate these issues. No additional mitigation actions are required beyond applying this official update.