CVE-2026-6761 is a high-severity privilege escalation vulnerability affecting the Networking component of Mozilla Firefox. The flaw allows an attacker to escalate privileges, potentially impacting confidentiality, integrity, and availability. The vulnerability is tracked under CWE-269 (Improper Privilege Management). Mozilla fixed this issue in Firefox 150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10. The vendor advisories (MFSA 2026-30 and MFSA 2026-32) provide detailed information and confirm the fix. No evidence of exploitation in the wild has been reported.

Successful exploitation of this vulnerability could allow an attacker to escalate privileges within the affected Firefox or Thunderbird environment, potentially leading to full compromise of the application context. The CVSS vector indicates network attack vector, low attack complexity, no privileges required, user interaction required, and high impact on confidentiality, integrity, and availability. However, no known exploits have been observed in the wild.

Mozilla has fixed this vulnerability in Firefox 150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10. Users and administrators should update to these versions or later to remediate the vulnerability. Since this is not a cloud service, patching the client software is required. There are no vendor advisories indicating that no action is required or that the issue is already mitigated without patching.