CVE-2026-63567 — IesEngine checks padding before MAC in block-cipher mode (CBC padding oracle)

Legion of the Bouncy Castle Inc. bc-csharp before version 2.7.0 contains an observable discrepancy in IesEngine.DecryptBlock that may allow a remote attacker to recover plaintext from an IES or ECIES ciphertext if the attacker has captured the ciphertext and can submit modified ciphertexts for decryption under the same key pair.