The remote host is missing an update to tiff announced via advisory DSA 1632-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%201632-1

Drew Yao discovered that libTIFF, a library for handling the Tagged Image File Format, is vulnerable to a programming error allowing malformed tiff files to lead to a crash or execution of arbitrary code. For the stable distribution (etch), this problem has been fixed in version 3.8.2-7+etch1. For the testing distribution (lenny), this problem has been fixed in version 3.8.2-10+lenny1. The unstable distribution (sid) will be fixed soon. We recommend that you upgrade your tiff package.