The demangle_template_value_parm and do_hpacc_template_literal functions in cplus-dem.c in libiberty allow remote attackers to cause a denial of service (out-of-bounds read and crash) via a crafted binary.
https://gcc.gnu.org/ml/gcc-patches/2016-05/msg00223.html
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70926