The remote host is missing an update to firefox-sage announced via advisory DSA 1951-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%201951-1

It was discovered that firefox-sage, a lightweight RSS and Atom feed reader for Firefox, does not sanitise the RSS feed information correctly, which makes it prone to a cross-site scripting and a cross-domain scripting attack. For the stable distribution (lenny), this problem has been fixed in version 1.4.2-0.1+lenny1. For the oldstable distribution (etch), this problem has been fixed in version 1.3.6-4etch1. For the testing distribution (squeeze) and the unstable distribution (sid), this problem has been fixed in version 1.4.3-3. We recommend that you upgrade your firefox-sage packages.