CVE-2026-8971: Mozilla Firefox

Medium severity, CVSS 6.5. EPSS: 0.2% chance of exploitation in the next 30 days.

Same-origin policy bypass in the Networking: JAR component. This vulnerability was fixed in Firefox 151 and Thunderbird 151.

Affected products

• Mozilla Firefox: before 151.0.0 (fixed in 151.0.0)
• Mozilla Thunderbird: before 151.0.0 (fixed in 151.0.0)

Published 2026-05-19. Last modified 2026-07-23.