source: https://www.securityfocus.com/bid/7637/info The cupsd has been reported prone to a denial of service vulnerability. Reportedly the cupsd does not adequately apply a time-out process for malicious HTTP requests and service is denied to subsequent cupsd requests. This issue may be exploited by remote attackers to deny cupsd service to valid users. $ telnet <your_favorite_cups_server> ipp POST /printers/<your_favorite_printer> HTTP/1.1 Don't enter the second carriage return to complete the headers, just the POST line and one carriage return.