CVE-2021-29969

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

Description

If Thunderbird was configured to use STARTTLS for an IMAP connection, and an attacker injected IMAP server responses prior to the completion of the STARTTLS handshake, then Thunderbird didn't ignore the injected data. This could have resulted in Thunderbird showing incorrect information, for example the attacker could have tricked Thunderbird to show folders that didn't exist on the IMAP server. This vulnerability affects Thunderbird < 78.12.

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-2021-29969

vendor Authored 2026-05-27

Vendor advisory: rocky — https://errata.rockylinux.org/RLSA-2021:2883

vendor Authored 2026-05-27

Vendor advisory: suse — https://www.suse.com/security/cve/CVE-2021-29969.html

vendor Authored 2026-05-27

Vendor advisory: arch — https://security.archlinux.org/ASA-202107-21

OS impact

OSVersionStatusFixed in
arch archfixed78.12.0-1
suse slesaffected
rockylinux rocky8fixed
debian debianbookwormfixed1:78.12.0-1
debian debianbullseyefixed1:78.12.0-1
debian debianforkyfixed1:78.12.0-1
debian debiansidfixed1:78.12.0-1
debian debiantrixiefixed1:78.12.0-1

References

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