CGI versions from 4.71 before 5.00 for Perl allow denial of service via a plain string dereferenced as a symbolic reference in uploadInfo.
uploadInfo dereferences its argument and calls its filename method without checking that it is an upload filehandle. A plain string naming a defined global variable, such as the parameter value from ?upload=0, is treated as a symbolic reference, and the method call on it dies.
Access of Resource Using Incompatible Type The product allocates or initializes a resource such as a pointer, object, or variable using one type, but it later accesses that resource using a type that is incompatible with the original type.