Constrata's coordinator transit engine `ciphertextContainer.UnmarshalJSON` panics on attacker-controlled short ciphertexts

Summary ciphertextContainer.UnmarshalJSON decodes the third :-separated component of a vault:vX:base64... ciphertext and then unconditionally takes a 12-byte prefix slice for the AES-GCM nonce: c.nonce = fullCiphertext:aesGCMNonceSize. If the decoded blob is shorter than 12 bytes, the slice...