CVE-2021-4129

CRITICAL

Firefox < 95.0 and Firefox ESR < 91.4.0 - Out-of-bounds Write

Title source: llm

Description

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.

References (4)

Core 4

Core References

Exploit, Issue Tracking, Vendor Advisory

https://bugzilla.mozilla.org/buglist.cgi?bug_id=1393362%2C1736046%2C1736751%2C1737009%2C1739372%2C1739421

Vendor Advisory

https://www.mozilla.org/security/advisories/mfsa2021-52/

Vendor Advisory

https://www.mozilla.org/security/advisories/mfsa2021-53/

Vendor Advisory

https://www.mozilla.org/security/advisories/mfsa2021-54/

Scores

CVSS v3 9.8

EPSS 0.0031

EPSS Percentile 54.3%

Attack Vector NETWORK

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

CISA SSVC

Vulnrichment

Exploitation none

Automatable yes

Technical Impact total

Details

CWE

CWE-787

Status published

Products (3)

mozilla/firefox < 95.0

mozilla/firefox_esr < 91.4.0

mozilla/thunderbird < 91.4.0

Published Dec 22, 2022

Tracked Since Feb 18, 2026