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) opreceive, (2) opstart, (3) opstartandreceive, (4) opsend, (5) opstartandsend, and (6) opstartsendandreceive XDR requests, which triggers memory corruption.