CVE-2021-29967

high
Published — · Modified —
CVSS v3
CVSS v2
VIR risk
8.0

Description

Mozilla developers reported memory safety bugs present in Firefox 88 and Firefox ESR 78.11. 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 Thunderbird < 78.11, Firefox < 89, and Firefox ESR < 78.11.

Predictions

Exploit likelihood
20%
Patch ETA

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

vendor Authored 2026-05-27

Vendor advisory: rocky — https://errata.rockylinux.org/RLSA-2021:2233

vendor Authored 2026-05-27

Vendor advisory: rocky — https://errata.rockylinux.org/RLSA-2021:2264

vendor Authored 2026-05-27

Vendor advisory: debian — https://security-tracker.debian.org/tracker/CVE-2021-29967

vendor Authored 2026-05-27

Vendor advisory: arch — https://security.archlinux.org/ASA-202106-3

vendor Authored 2026-05-27

Vendor advisory: arch — https://security.archlinux.org/ASA-202106-22

OS impact

OSVersionStatusFixed in
arch archfixed78.11.0-1
debian debiansidfixed89.0-1
debian debianbookwormfixed78.11.0esr-1
debian debianbullseyefixed78.11.0esr-1
debian debianforkyfixed78.11.0esr-1
debian debiantrixiefixed78.11.0esr-1
rockylinux rocky8fixed

References

Verify integrity in audit chain (admin only). AS-IS.