CVE-2021-40529: Use of a Broken or Risky Cryptographic Algorithm

The ElGamal implementation in Botan, as used in Thunderbird and other products, 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.