The remote host is missing an update to icedove announced via advisory DSA 2437-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%202437-1

Several vulnerabilities have been discovered in Icedove, an unbranded version of the Thunderbird mail/news client. CVE-2012-0455 Soroush Dalili discovered that a cross-site scripting countermeasure related to Javascript URLs could be bypassed. CVE-2012-0456 Atte Kettunen discovered an out of bounds read in the SVG Filters, resulting in memory disclosure. CVE-2012-0458 Mariusz Mlynski discovered that privileges could be escalated through a Javascript URL as the home page. CVE-2012-0461 Bob Clary discovered memory corruption bugs, which may lead to the execution of arbitrary code. For the stable distribution (squeeze), this problem has been fixed in version icedove 3.0.11-1+squeeze8. For the unstable distribution (sid), this problem will be fixed soon. We recommend that you upgrade your icedove packages.