CVE-2021-4129

Mozilla Firefox ESR and 3 others: Out-of-bounds Write

CVE-2021-4129 is fixed in 10 products on 2 platforms, first by Mozilla Thunderbird (en-US) 91.4.0, released December 3, 2021. It is not reported as exploited. Patch Radar priority: High.

HighFixed on 2 platforms
CVSS
9.8
Important
Exploitation
None reported
No vendor assessment
CISA KEV
Not listed
Not in the Known Exploited Vulnerabilities catalog
EPSS
0.0106
64th percentile

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.

Where it's fixed

ProductFixed inFixReleased
Windows apps
Mozilla Firefox ESR (en-US) 102.0 Mozilla Firefox ESR (en-US) 102.0 Jun 23, 2022
Mozilla Thunderbird (en-US) 91.4.0 Mozilla Thunderbird (en-US) 91.4.0 Dec 3, 2021
Linux
firefox · RHEL 8 0:91.4.0-1.el8_5 RHSA-2021:5013 Dec 8, 2021
firefox · rocky 8 0:91.4.0-1.el8_5 RLSA-2021:5013 Dec 8, 2021
firefox-esr · Debian 12.15 (bookworm) 91.4.0esr-1 DEBIAN-CVE-2021-4129 Dec 22, 2022
firefox-esr · Debian 13.5 (trixie) 91.4.0esr-1 DEBIAN-CVE-2021-4129 Dec 22, 2022
firefox-esr · Debian 14 91.4.0esr-1 DEBIAN-CVE-2021-4129 Dec 22, 2022
thunderbird · Debian 12.15 (bookworm) 1:91.4.0-1 DEBIAN-CVE-2021-4129 Dec 22, 2022
thunderbird · Debian 13.5 (trixie) 1:91.4.0-1 DEBIAN-CVE-2021-4129 Dec 22, 2022
thunderbird · Debian 14 1:91.4.0-1 DEBIAN-CVE-2021-4129 Dec 22, 2022
thunderbird · RHEL 8 0:91.4.0-2.el8_5 RHSA-2021:5045 Dec 9, 2021
thunderbird · Ubuntu 18.04.6 LTS (bionic) 1:91.5.0+build1-0ubuntu0.18.04.1 thunderbird 1:91.5.0+build1-0ubuntu0.18.04.1 Feb 16, 2023
thunderbird · Ubuntu 20.04 LTS (focal) 1:91.5.0+build1-0ubuntu0.20.04.1 thunderbird 1:91.5.0+build1-0ubuntu0.20.04.1 Feb 16, 2023
thunderbird · rocky 8 0:91.4.0-2.el8_5 RLSA-2021:5045 Dec 9, 2021
thunderbird-gnome-support · Ubuntu 18.04.6 LTS (bionic) 1:91.5.0+build1-0ubuntu0.18.04.1 thunderbird-gnome-support 1:91.5.0+build1-0ubuntu0.18.04.1 Feb 16, 2023
thunderbird-gnome-support · Ubuntu 20.04 LTS (focal) 1:91.5.0+build1-0ubuntu0.20.04.1 thunderbird-gnome-support 1:91.5.0+build1-0ubuntu0.20.04.1 Feb 16, 2023
thunderbird-mozsymbols · Ubuntu 18.04.6 LTS (bionic) 1:91.5.0+build1-0ubuntu0.18.04.1 thunderbird-mozsymbols 1:91.5.0+build1-0ubuntu0.18.04.1 Feb 16, 2023
thunderbird-mozsymbols · Ubuntu 20.04 LTS (focal) 1:91.5.0+build1-0ubuntu0.20.04.1 thunderbird-mozsymbols 1:91.5.0+build1-0ubuntu0.20.04.1 Feb 16, 2023
xul-ext-calendar-timezones · Ubuntu 18.04.6 LTS (bionic) 1:91.5.0+build1-0ubuntu0.18.04.1 xul-ext-calendar-timezones 1:91.5.0+build1-0ubuntu0.18.04.1 Feb 16, 2023
xul-ext-calendar-timezones · Ubuntu 20.04 LTS (focal) 1:91.5.0+build1-0ubuntu0.20.04.1 xul-ext-calendar-timezones 1:91.5.0+build1-0ubuntu0.20.04.1 Feb 16, 2023
xul-ext-gdata-provider · Ubuntu 18.04.6 LTS (bionic) 1:91.5.0+build1-0ubuntu0.18.04.1 xul-ext-gdata-provider 1:91.5.0+build1-0ubuntu0.18.04.1 Feb 16, 2023
xul-ext-gdata-provider · Ubuntu 20.04 LTS (focal) 1:91.5.0+build1-0ubuntu0.20.04.1 xul-ext-gdata-provider 1:91.5.0+build1-0ubuntu0.20.04.1 Feb 16, 2023
xul-ext-lightning · Ubuntu 18.04.6 LTS (bionic) 1:91.5.0+build1-0ubuntu0.18.04.1 xul-ext-lightning 1:91.5.0+build1-0ubuntu0.18.04.1 Feb 16, 2023
xul-ext-lightning · Ubuntu 20.04 LTS (focal) 1:91.5.0+build1-0ubuntu0.20.04.1 xul-ext-lightning 1:91.5.0+build1-0ubuntu0.20.04.1 Feb 16, 2023

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