CVE-2021-23991

6.8 mediumEPSS 1.0%

Medium (6.8) in mozilla thunderbird. EPSS 1.0% chance of exploitation in the next 30 days.

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.

Severity

CVSS 3.1

6.8 medium

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N

EPSS: 1.0% chance of exploitation in the next 30 days; higher than 63% of CVEs (scores of 2026-10-31)
Published: 2021-06-24
Modified: 2026-06-17
Record from: the NVD, synced 2026-10-19

Affected

mozilla:thunderbird

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1673240
https://www.mozilla.org/security/advisories/mfsa2021-13/
https://bugzilla.mozilla.org/show_bug.cgi?id=1673240
https://www.mozilla.org/security/advisories/mfsa2021-13/

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