CVE-2021-29977

high

Published — · Modified —

CVSS v3

—

CVSS v2

—

VIR risk

8.0

Description

Mozilla developers reported memory safety bugs present in Firefox 89. 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 < 90.

Predictions

Exploit likelihood

20%

Patch ETA

—

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

vendor Authored 2026-05-27

Vendor advisory: debian — https://security-tracker.debian.org/tracker/CVE-2021-29977

vendor Authored 2026-05-27

Vendor advisory: suse — https://www.suse.com/security/cve/CVE-2021-29977.html

vendor Authored 2026-05-27

Vendor advisory: arch — https://security.archlinux.org/ASA-202107-20

OS impact

OS	Version	Status	Fixed in
arch		fixed	`90.0-1`
sles		affected
debian	sid	fixed	`90.0-1`

References

https://security.archlinux.org/ASA-202107-20
https://www.suse.com/security/cve/CVE-2021-29977.html
https://security-tracker.debian.org/tracker/CVE-2021-29977

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