CVE-2026-8955 is a privilege escalation vulnerability affecting the DOM: Workers component in Mozilla Firefox. Privilege escalation vulnerabilities allow an attacker to gain higher privileges than intended, potentially leading to unauthorized actions within the browser context. Mozilla fixed this vulnerability in Firefox 151 and Firefox ESR 140.11 as part of a security advisory addressing multiple issues. The vulnerability was reported by researcher lebr0nli and is rated with moderate impact. There is no CVSS score provided. No known exploits in the wild have been documented. The vendor advisory confirms the fix is available in the specified Firefox versions.

The vulnerability allows privilege escalation within the DOM: Workers component, which could enable an attacker to perform actions with elevated privileges in the browser environment. Mozilla classifies the impact as moderate. There are no reports of active exploitation in the wild. The issue is mitigated by updating to Firefox 151 or Firefox ESR 140.11.

Mozilla has released official fixes for this vulnerability in Firefox 151 and Firefox ESR 140.11. Users and administrators should update affected Firefox installations to these versions or later to remediate the issue. No additional mitigation steps are required beyond applying the official update.