Integer overflow in Firebird SQL 1.0.3 and earlier, 1.5.x before 1.5.6, 2.0.x before 2.0.4, and 2.1.x before 2.1.0 RC1 might allow remote attackers to execute arbitrary code via crafted (1) op_receive, (2) op_start, (3) op_start_and_receive, (4) op_send, (5) op_start_and_send, and (6) op_start_send_and_receive XDR requests, which triggers memory corruption.