A flaw was found in the way signature calculation is handled by cephx protocol. The signature calculation is encrypting a 29 byte struct with 16-byte block AES cipher, and then using the first 8 bytes of the result as signature. This only covers first (16 by tes) cipher block, datacrc falls on second block.There are no known exploits against this, If attacker can alter the message payload any changes in datacrc will not be noticed or checked by signature check.