CVE-2026-84136: Vulnerability in Mozilla Firefox

This vulnerability concerns an issue in the DOM Navigation component of Mozilla Firefox, identified as CVE-2026-84136. It was discovered internally and fixed in Firefox 155 and Firefox ESR 153.2. The vulnerability is categorized as an 'Other issue' with low impact. It is part of a large batch of security fixes addressing multiple high, moderate, and low impact vulnerabilities including use-after-free, sandbox escapes, privilege escalations, information disclosures, and site isolation issues. The CVSS score of 9.8 applies to the overall set of vulnerabilities fixed in these releases, not specifically to CVE-2026-84136. The vendor advisories confirm the fixes and recommend updating to the fixed versions.

The vulnerability could potentially allow information disclosure or other security-relevant defects related to the DOM Navigation component. However, the specific impact of CVE-2026-84136 is rated low by Mozilla. The overall set of vulnerabilities fixed in Firefox 155 and ESR 153.2 includes critical issues with high impact, but this particular CVE is not among the highest severity ones. No active exploitation in the wild has been reported.

Mozilla has released official fixes for this vulnerability in Firefox 155 and Firefox ESR 153.2. Users and administrators should update to these versions or later to remediate the vulnerability. Since the vendor advisory confirms the fix, no additional mitigation steps are required beyond applying the official updates.