Tor before 0.2.4.23 and 0.2.5 before 0.2.5.6-alpha maintains a circuit after an inbound RELAY_EARLY cell is received by a client, which makes it easier for remote attackers to conduct traffic-confirmation attacks by using the pattern of RELAY and RELAY_EARLY cells as a means of communicating information about hidden service names.
Exploitability
AV:NAC:MAu:NImpact
C:PI:PA:N5.8/AV:N/AC:M/Au:N/C:P/I:P/A:N