Fuji Xerox Printing Systems (FXPS) print engine, as used in products including (1) Dell 3000cn through 5110cn and (2) Fuji Xerox DocuPrint firmware before 20060628 and Network Option Card firmware before 5.13, allows remote attackers to use the FTP printing interface as a proxy ("FTP bounce") by using arbitrary PORT arguments to connect to systems for which access would be otherwise restricted.