CVE-2021-40530: Cryptopp Crypto++

Medium severity, CVSS 5.9. EPSS: 1.2% chance of exploitation in the next 30 days.

The ElGamal implementation in Crypto++ through 8.5 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

• Cryptopp Crypto++: up to and including 8.5
• Fedoraproject Fedora: version 33 only; version 34 only; version 35 only

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