The remote host is missing an update to netpbm-free announced via advisory DSA 1579-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%201579-1

A vulnerability was discovered in the GIF reader implementation in netpbm-free, a suite of image manipulation utilities. Insufficient input data validation could allow a maliciously-crafted GIF file to overrun a stack buffer, potentially permitting the execution of arbitrary code. For the stable distribution (etch), these problems have been fixed in version 2:10.0-11.1+etch1. For the unstable distribution (sid), these problems were fixed in version 2:10.0-11.1. We recommend that you upgrade your netpbm packages.