The chkpass extension in PostgreSQL before 8.4.20, 9.0.x before 9.0.16, 9.1.x before 9.1.12, 9.2.x before 9.2.7, and 9.3.x before 9.3.3 does not properly check the return value of the crypt library function, which allows remote authenticated users to cause a denial of service (NULL pointer dereference and crash) via unspecified vectors.