The remote host is missing an update to gpdf announced via advisory DSA 1354-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%201354-1

It was discovered that an integer overflow in xpdf PDF viewer may lead to the execution of arbitrary code if a malformed PDF file is opened. gpdf includes a copy of the xpdf code and requires an update as well. For the oldstable distribution (sarge) this problem has been fixed in version 2.8.2-1.2sarge6. The stable distribution (etch) no longer contains gpdf. The unstable distribution (sid) no longer contains gpdf. We recommend that you upgrade your gpdf packages.