The remote host is missing an update to tor announced via advisory DSA 2363-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%202363-1

It was discovered that Tor, an online privacy tool, incorrectly computes buffer sizes in certain cases involving SOCKS connections. Malicious parties could use this to cause a heap-based buffer overflow, potentially allowing execution of arbitrary code. In Tor's default configuration this issue can only be triggered by clients that can connect to Tor's socks port, which listens only on localhost by default. In non-default configurations where Tor's SocksPort listens not only on localhost or where Tor was configured to use another socks server for all of its outgoing connections, Tor is vulnerable to a larger set of malicious parties. For the oldstable distribution (lenny), this problem has been fixed in version 0.2.1.32-1. For the stable distribution (squeeze), this problem has been fixed in version 0.2.2.35-1~squeeze+1. For the unstable and testing distributions, this problem has been fixed in version 0.2.2.35-1. For the experimental distribution, this problem has has fixed in version 0.2.3.10-alpha-1. We recommend that you upgrade your tor packages.