CVE-2021-4129criticalCWE-787

CVE-2021-4129: critical vulnerability in Mozilla Firefox

Published 22 Dec 2022 · Updated 16 Apr 2025

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28Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 9.8epss 1.1%

Mozilla developers and community members Julian Hector, Randell Jesup, Gabriele Svelto, Tyson Smith, Christian Holler, and Masayuki Nakano reported memory safety bugs present in Firefox 94. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 95, Firefox ESR < 91.4.0, and Thunderbird < 91.4.0.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

Mozilla · Firefox Mozilla · Firefox ESR Mozilla · Thunderbird

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References

https://bugzilla.mozilla.org/buglist.cgi?bug_id=1393362%2C1736046%2C1736751%2C1737009%2C1739372%2C1739421 https://www.mozilla.org/security/advisories/mfsa2021-52/https://www.mozilla.org/security/advisories/mfsa2021-53/https://www.mozilla.org/security/advisories/mfsa2021-54/