Tor is an implementation of second generation Onion Routing, a connection-oriented anonymizing communication service.
Some integer overflows exist when adding elements to the smartlists. Non-printable characters received from the network are not properly sanitised before being logged. There are additional unspecified bugs in the directory server and in the internal circuits.
The possible buffer overflow may allow a remote attacker to execute arbitrary code on the server by sending large inputs. The other vulnerabilities can lead to a Denial of Service, a lack of logged information, or some information disclosure.
There is no known workaround at this time.
All Tor users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose net-misc/tor