The send_dg function in resolv/res_send.c in GNU C Library (aka glibc or libc6) before 2.20 does not properly reuse file descriptors, which allows remote attackers to send DNS queries to unintended locations via a large number of request that trigger a call to the getaddrinfo function. http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2013-7423
