CVE-2020-26974

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

Description

When flex-basis was used on a table wrapper, a StyleGenericFlexBasis object could have been incorrectly cast to the wrong type. This resulted in a heap user-after-free, memory corruption, and a potentially exploitable crash. This vulnerability affects Firefox < 84, Thunderbird < 78.6, and Firefox ESR < 78.6.

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-2020-26974

vendor Authored 2026-05-27

Vendor advisory: suse — https://www.suse.com/security/cve/CVE-2020-26974.html

vendor Authored 2026-05-27

Vendor advisory: arch — https://security.archlinux.org/ASA-202012-25

vendor Authored 2026-05-27

Vendor advisory: arch — https://security.archlinux.org/ASA-202012-23

OS impact

OSVersionStatusFixed in
arch archfixed78.6.0-1
suse slesaffected
debian debiansidfixed84.0-1
debian debianbookwormfixed78.6.0esr-1
debian debianbullseyefixed78.6.0esr-1
debian debianforkyfixed78.6.0esr-1
debian debiantrixiefixed78.6.0esr-1

References

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