CVE-2026-74942 is a privilege escalation vulnerability affecting the Remote Settings Client component in Mozilla Firefox. It allows an attacker to gain elevated privileges within the browser environment. The vulnerability was fixed in Firefox 154 and Firefox ESR versions 115.39, 140.14, and 153.1. The fix is part of a broader security update addressing multiple high-impact vulnerabilities. The vulnerability was reported by Gal Ankonina and is classified as high impact by Mozilla. There is no CVSS score provided, and no known active exploitation has been reported.

Successful exploitation of this vulnerability could allow an attacker to escalate privileges within the Firefox browser, potentially enabling unauthorized actions or access to restricted browser functionality. The vendor classifies the impact as high. No evidence of active exploitation in the wild has been reported.

Users and administrators should update Mozilla Firefox to version 154 or later, or Firefox ESR to versions 115.39, 140.14, or 153.1 or later, where this vulnerability has been fixed. Applying these official updates fully mitigates the vulnerability. No additional mitigation actions are required beyond applying the vendor-provided patches.