The demangler in GNU Libiberty allows remote attackers to cause a denial of service (infinite loop, stack overflow, and crash) via a cycle in the references of remembered mangled types.
https://gcc.gnu.org/ml/gcc-patches/2016-06/msg02030.html
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71696
http://www.securityfocus.com/bid/91519