Crypto++ (aka cryptopp) through 8.9.0 has a Marvin side channel during decryption with PKCS#1 v1.5 padding.

DISPUTED Crypto++ (aka Cryptopp) 8.6.0 and earlier contains a timing leakage in MakePublicKey(). There is a clear correlation between execution time and private key length, which may cause disclosure of the length information of the private key. This might allow attackers to conduct timing attacks. NOTE: this report is disputed by the vendor and multiple third parties. The execution-time differences are intentional. A user may make a choice of a longer key as a tradeoff between strength and performance. In making this choice, the amount of information leaked to an adversary is of infinitesimal value.

Crypto++ 8.3.0 and earlier contains a timing side channel in ECDSA signature generation. This allows a local or remote attacker, able to measure the duration of hundreds to thousands of signing operations, to compute the private key used. The issue occurs because scalar multiplication in ecp.cpp (prime field curves, small leakage) and algebra.cpp (binary field curves, large leakage) is not constant time and leaks the bit length of the scalar among other information.

Crypto++ (aka cryptopp) through 5.6.4 does not document the requirement for a compile-time NDEBUG definition disabling the many assert calls that are unintended in production use, which might allow context-dependent attackers to obtain sensitive information by leveraging access to process memory after an assertion failure, as demonstrated by reading a core dump.