The std::random_device class in libstdc++ in the GNU Compiler Collection (aka GCC) before 4.9.4 does not properly handle short reads from blocking sources, which makes it easier for context-dependent attackers to predict the random values via unspecified vectors.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65142
https://bugzilla.redhat.com/show_bug.cgi?id=1262846
http://www.securitytracker.com/id/1034375
http://lists.opensuse.org/opensuse-updates/2016-04/msg00052.html
http://lists.opensuse.org/opensuse-updates/2015-11/msg00054.html