The remote host is missing an update to ejabberd announced via advisory DSA 1774-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%201774-1

It was discovered that ejabberd, a distributed, fault-tolerant Jabber/XMPP server, does not sufficiently sanitise MUC logs, allowing remote attackers to perform cross-site scripting (XSS) attacks. For the stable distribution (lenny), this problem has been fixed in version 2.0.1-6+lenny1. The oldstable distribution (etch) is not affected by this issue. For the testing distribution (squeeze), this problem will be fixed soon. For the unstable distribution (sid), this problem has been fixed in version 2.0.5-1. We recommend that you upgrade your ejabberd packages.