CVE-2021-23991

medium
Published — · Modified —
CVSS v3
CVSS v2
VIR risk
5.5

Description

If a Thunderbird user has previously imported Alice's OpenPGP key, and Alice has extended the validity period of her key, but Alice's updated key has not yet been imported, an attacker may send an email containing a crafted version of Alice's key with an invalid subkey, Thunderbird might subsequently attempt to use the invalid subkey, and will fail to send encrypted email to Alice. This vulnerability affects Thunderbird < 78.9.1.

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-2021-23991

vendor Authored 2026-05-27

Vendor advisory: suse — https://www.suse.com/security/cve/CVE-2021-23991.html

OS impact

OSVersionStatusFixed in
arch archfixed78.9.1-1
suse slesaffected
debian debianbookwormfixed1:78.10.0-1
debian debianbullseyefixed1:78.10.0-1
debian debianforkyfixed1:78.10.0-1
debian debiansidfixed1:78.10.0-1
debian debiantrixiefixed1:78.10.0-1

References

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