socat 1.2.0.0 before 1.7.2.2 and 2.0.0-b1 before 2.0.0-b6, when used for a listen type address and the fork option is enabled, allows remote attackers to cause a denial of service (file descriptor consumption) via multiple request that are refused based on the (1) sourceport, (2) lowport, (3) range, or (4) tcpwrap restrictions.