CVE-2021-29971: Mozilla Firefox

Critical severity, CVSS 9.8. EPSS: 1% chance of exploitation in the next 30 days.

If a user had granted a permission to a webpage and saved that grant, any webpage running on the same host - irrespective of scheme or port - would be granted that permission. *This bug only affects Firefox for Android. Other operating systems are unaffected.*. This vulnerability affects Firefox < 90.

Affected products

• Mozilla Firefox: before 90.0 (fixed in 90.0)

Published 2021-08-05. Last modified 2026-06-17.