CVE-2026-7321: Mozilla Firefox

Critical severity, CVSS 9.6. EPSS: 0.4% chance of exploitation in the next 30 days.

Sandbox escape due to incorrect boundary conditions in the WebRTC: Networking component. This vulnerability was fixed in Firefox 150, Thunderbird 150, Firefox ESR 140.10.1, and Thunderbird 140.10.1.

Affected products

• Mozilla Firefox: before 140.10.1 (fixed in 140.10.1); before 150.0 (fixed in 150.0)
• Mozilla Thunderbird: before 140.10.1 (fixed in 140.10.1); before 150.0 (fixed in 150.0)

Published 2026-04-28. Last modified 2026-06-17.