CVE-2021-23991
Mozilla: An attacker may use Thunderbird's OpenPGP key refresh mechanism to poison an existing key
Severity
ModerateRed Hat Product Security
CVSS 3.1
Review impact separately from score.
Published · April 8, 2021
Updated · November 22, 2025
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.
CVSS score applicability
The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.
Mitigation
No mitigation is specified in collected source.
CVSS / CWE
CVSS 3.1 · 6.8CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N
CWE-347 · Improper Verification of Cryptographic Signature