CVE-2026-8391: Mozilla Firefox

Medium severity, CVSS 5.3. EPSS: 0.6% chance of exploitation in the next 30 days.

Other issue in the JavaScript Engine component. This vulnerability was fixed in Firefox 150.0.3, Firefox ESR 115.36, Firefox ESR 140.11, and Thunderbird 140.11.

Affected products

• Mozilla Firefox: before 150.0.3 (fixed in 150.0.3)

Published 2026-05-12. Last modified 2026-07-15.