Lasse Overlier and Paul Syverson have reported a weakness in Tor, which can be exploited by malicious people to disclose certain sensitive information.

The weakness is caused due to a design error in Tor. This can be exploited to reveal the location of a hidden service more quickly than was previously thought by setting up a malicious Tor server and accessing the hidden service repeatedly while keeping track of who builds circuits through the malicious server shortly after each access.

The weakness has been reported in all stable versions and all experimental versions through 0.1.1.10-alpha.

Solution
Update to version 0.1.1.20.
Further details available to Secunia VIM customers

Provided and/or discovered by
Lasse Overlier and Paul Syverson

Changelog
Further details available to Secunia VIM customers

Original Advisory
http://archives.seul.org/or/announce/Jan-2006/msg00001.html
http://archives.seul.org/or/announce/May-2006/msg00000.html

Deep Links
Links available to Secunia VIM customers