CVE-2021-29983: Mozilla Firefox

Medium severity, CVSS 6.5. EPSS: 0.7% chance of exploitation in the next 30 days.

Firefox for Android could get stuck in fullscreen mode and not exit it even after normal interactions that should cause it to exit. *Note: This issue only affected Firefox for Android. Other operating systems are unaffected.*. This vulnerability affects Firefox < 91.

Affected products

• Mozilla Firefox: before 91.0 (fixed in 91.0)

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