The remote host is missing an update to libwmf announced via advisory DSA 1796-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%201796-1

Tavis Ormandy discovered that the embedded GD library copy in libwmf, a library to parse windows metafiles (WMF), makes use of a pointer after it was already freed. An attacker using a crafted WMF file can cause a denial of service or possibly the execute arbitrary code via applications using this library. For the oldstable distribution (etch), this problem has been fixed in version 0.2.8.4-2+etch1. For the stable distribution (lenny), this problem has been fixed in version 0.2.8.4-6+lenny1. For the testing distribution (squeeze), this problem will be fixed soon. For the unstable distribution (sid), this problem has been fixed in version 0.2.8.4-6.1. We recommend that you upgrade your libwmf packages.