CVE-2021-40528: Gnupg Libgcrypt

Medium severity, CVSS 5.9. EPSS: 1.4% chance of exploitation in the next 30 days.

The ElGamal implementation in Libgcrypt before 1.9.4 allows plaintext recovery because, during interaction between two cryptographic libraries, a certain dangerous combination of the prime defined by the receiver's public key, the generator defined by the receiver's public key, and the sender's ephemeral exponents can lead to a cross-configuration attack against OpenPGP.

Affected products

• Gnupg Libgcrypt: before 1.9.4 (fixed in 1.9.4)

Published 2021-09-06. Last modified 2026-06-17.