CVE-2021-29971

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.0% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-08-05 · updated 2026-06-17
Weakness: CWE-281

Description

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

How to fix

Upgrade to a fixed version: Mozilla Firefox 90.0. Check the vendor advisory for mitigations.

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1713638
https://www.mozilla.org/security/advisories/mfsa2021-28/
https://bugzilla.mozilla.org/show_bug.cgi?id=1713638
https://www.mozilla.org/security/advisories/mfsa2021-28/

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