The remote host is missing an update to iceweasel announced via advisory DSA 2400-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%202400-1

Several vulnerabilities have been discovered in Iceweasel, a web browser based on Firefox. The included XULRunner library provides rendering services for several other applications included in Debian. CVE-2011-3670 Gregory Fleischer discovered that IPv6 URLs were incorrectly parsed, resulting in potential information disclosure. CVE-2012-0442 Jesse Ruderman and Bob Clary discovered memory corruption bugs, which may lead to the execution of arbitrary code. CVE-2012-0444 regenrecht discovered that missing input sanisiting in the Ogg Vorbis parser may lead to the execution of arbitrary code. CVE-2012-0449 Nicolas Gregoire and Aki Helin discovered that missing input sanisiting in XSLT processing may lead to the execution of arbitrary code. For the oldstable distribution (lenny), this problem has been fixed in version 1.9.0.19-13 of the xulrunner source package. For the stable distribution (squeeze), this problem has been fixed in version 3.5.16-12. For the unstable distribution (sid), this problem has been fixed in version 10.0-1. We recommend that you upgrade your iceweasel packages.