The remote host is missing an update to gnats announced via advisory DSA 590-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%20590-1

Khan Shirani discovered a format string vulnerability in gnats, the GNU problem report management system. This problem may be exploited to execute arbitrary code. For the stable distribution (woody) this problem has been fixed in version 3.999.beta1+cvs20020303-2. For the unstable distribution (sid) this problem has been fixed in version 4.0-7. We recommend that you upgrade your gnats package.