The remote host is missing an update to linux-2.6 announced via advisory DSA 1356-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%201356-1

Several local and remote vulnerabilities have been discovered in the Linux kernel that may lead to a denial of service or the execution of arbitrary code. For more details, please visit the referenced security advisories. These problems have been fixed in the stable distribution in version 2.6.18.dfsg.1-13etch1. The following matrix lists additional packages that were rebuilt for compatibility with or to take advantage of this update: Debian 4.0 (etch) fai-kernels 1.17+etch4 user-mode-linux 2.6.18-1um-2etch3 We recommend that you upgrade your kernel package immediately and reboot