The remote host is missing an update to pidgin announced via advisory DSA 2509-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%202509-1

Ulf Harnhammar found a buffer overflow in Pidgin, a multi protocol instant messaging client. The vulnerability can be exploited by an incoming message in the MXit protocol plugin. A remote attacker may cause a crash, and in some circumstances can lead to remote code execution. For the stable distribution (squeeze), this problem has been fixed in version 2.7.3-1+squeeze3. For the testing distribution (wheezy), this problem has been fixed in version 2.10.4-1.1. For the unstable distribution (sid), this problem has been fixed in version 2.10.6-1. We recommend that you upgrade your pidgin packages.