Tor before 0.1.2.15 can select a guard node beyond the first listed never-before-connected-to guard node, which allows remote attackers with control of certain guard nodes to obtain sensitive information and possibly leverage further attacks.

Tor before 0.1.2.14 can construct circuits in which an entry guard is in the same family as the exit node, which might compromise the anonymity of traffic sources and destinations by exposing traffic to inappropriate remote observers.