cryptopp -- ElGamal implementation allows plaintext recovery

Crypto++ 8.6 release notes reports:

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.