The getaddrinfo function in glibc before 2.15, when compiled with libidn and the AI_IDN flag is used, allows context-dependent attackers to cause a denial of service (invalid free) and possibly execute arbitrary code via unspecified vectors, as demonstrated by an internationalized domain name to ping6.
https://sourceware.org/git/gitweb.cgi?p=glibc.git%3Ba=commitdiff%3Bh=2e96f1c7
https://sourceware.org/bugzilla/show_bug.cgi?id=18011
https://bugzilla.redhat.com/show_bug.cgi?id=981942
https://bugzilla.redhat.com/show_bug.cgi?id=1186614
http://www.securityfocus.com/bid/72710