CVE-2021-29983

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.7% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-08-17 · updated 2026-06-17

Description

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

How to fix

Upgrade to a fixed version: Mozilla Firefox 91.0. Check the vendor advisory for mitigations.

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1719088
https://www.mozilla.org/security/advisories/mfsa2021-33/
https://bugzilla.mozilla.org/show_bug.cgi?id=1719088
https://www.mozilla.org/security/advisories/mfsa2021-33/

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