The ElGamal implementation in Botan through 2.18.1, 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.
eprint.iacr.org/2021/923
github.com/randombit/botan/pull/2790
ibm.github.io/system-security-research-updates/2021/07/20/insecurity-elgamal-pt1
ibm.github.io/system-security-research-updates/2021/09/06/insecurity-elgamal-pt2
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/72NB4OLD3VHJC3YF3PEP2HKF6BYURPAO/
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UPHGYWNJQKWLTUWBNSFB4F66MQDIL3IB/
security.gentoo.org/glsa/202208-14