CVE-2021-4128

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2022-12-22 · updated 2026-06-17
Weakness: CWE-416

Description

When transitioning in and out of fullscreen mode, a graphics object was not correctly protected; resulting in memory corruption and a potentially exploitable crash.<br>*This bug only affects Firefox on MacOS. Other operating systems are unaffected.*. This vulnerability affects Firefox < 95.

Affected products

Mozilla Firefox: before 95.0 — fixed in 95.0

How to fix

Upgrade to a fixed version: Mozilla Firefox 95.0. Check the vendor advisory for mitigations.

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1735852
https://www.mozilla.org/security/advisories/mfsa2021-52/
https://bugzilla.mozilla.org/show_bug.cgi?id=1735852
https://www.mozilla.org/security/advisories/mfsa2021-52/

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