The remote host is missing an update to fetchmail, fetchmail-ssl announced via advisory DSA 171-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%20171-1

Stefan Esser discovered several buffer overflows and a broken boundary check within fetchmail. If fetchmail is running in multidrop mode these flaws can be used by remote attackers to crash it or to execute arbitrary code under the user id of the user running fetchmail. Depending on the configuration this even allows a remote root compromise. These problems have been fixed in version 5.9.11-6.1 for both fetchmail and fetchmail-ssl for the current stable distribution (woody), in version 5.3.3-4.2 for fetchmail for the old stable distribution (potato) and in version 6.1.0-1 for both fetchmail and fetchmail-ssl for the unstable distribution (sid). There are no fetchmail-ssl packages for the old stable distribution (potato) and thus no updates. We recommend that you upgrade your fetchmail packages immediately.