The remote host is missing an update to mailman announced via advisory DSA 147-2.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%20147-2

Quoting DSA 147-1: A cross-site scripting vulnerability was discovered in mailman, a software to manage electronic mailing lists. When a properly crafted URL is accessed with Internet Explorer (other browsers don't seem to be affected), the resulting webpage is rendered similar to the real one, but the javascript component is executed as well, which could be used by an attacker to get access to sensitive information. The new version for Debian 2.2 also includes backports of security related patches from mailman 2.0.11. This has been fixed in DSA 147-1 already, however, contrary to popular belief, it turned out that the Python packaging does not upgrade Python 1.5 users to 2.1 when upgrading from potato to woody. It also turned out that the mailman security update unwittingly introduced a dependency to Python 2.1, both in the security update and upstream, which left the package unusable on some systems. This problem has been fixed in version 2.0.11-1woody4 for the current stable distribution (woody). Others are not affected. We recommend that you upgrade your mailman package.