The remote host is missing an update to tiff announced via advisory DSA 2575-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%202575-1

It was discovered that ppm2tiff of the tiff tools, a set of utilities for TIFF manipulation and conversion, is not properly checking the return value of an internal function used in order to detect integer overflows. As a consequence, ppm2tiff suffers of a heap-based buffer overflow. This allows attacker to potentially execute arbitrary code via a crafted ppm image, especially in scenarios in which images are automatically processed. For the stable distribution (squeeze), this problem has been fixed in version 3.9.4-5+squeeze7. For the testing distribution (wheezy), this problem will be fixed soon. For the unstable distribution (sid), this problem has been fixed in version 4.0.2-5. We recommend that you upgrade your tiff packages.