Vulnerability in Mozilla Thunderbird

CVE-2021-23991

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.

EPSS: 0.010 (60.4th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 6.8 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N.

Affected products

References

Frequently asked questions

What is CVE-2021-23991?
CVE-2021-23991 is a medium-severity vulnerability in Mozilla Thunderbird. CVSS score: 6.8/10. Published 2021-06-24.
How severe is CVE-2021-23991?
Medium severity. CVSS v3 base score is 6.8 out of 10.