cURL is a tool for getting files from FTP, HTTP, Gopher, Telnet, and Dict servers, using any of the supported protocols. cURL is designed to work without user interaction or any kind of interactivity. Scott Cantor reported that cURL is affected by the previously published "null prefix attack", caused by incorrect handling of NULL characters in X.509 certificates. If an attacker is able to get a carefully-crafted certificate signed by a trusted Certificate Authority, the attacker could use the certificate during a man-in-the-middle attack and potentially confuse cURL into accepting it by mistake. cURL users should upgrade to these updated packages, which contain a backported patch to correct these issues. All running applications using libcurl must be restarted for the update to take effect.