Tor before 0.2.4.20, when OpenSSL 1.x is used in conjunction with a certain HardwareAccel setting on Intel Sandy Bridge and Ivy Bridge platforms, does not properly generate random numbers for (1) relay identity keys and (2) hidden-service identity keys, which might make it easier for remote attackers to bypass cryptographic protection mechanisms via unspecified vectors.
https://lists.torproject.org/pipermail/tor-talk/2013-December/031483.html
http://lists.opensuse.org/opensuse-updates/2014-01/msg00095.html