The remote host is missing an update to mod-auth-shadow announced via advisory DSA 421-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%20421-1

David B Harris discovered a problem with mod-auth-shadow, an Apache module which authenticates users against the system shadow password database, where the expiration status of the user's account and password were not enforced. This vulnerability would allow an otherwise authorized user to successfully authenticate, when the attempt should be rejected due to the expiration parameters. For the current stable distribution (woody) this problem has been fixed in version 1.3-3.1woody.1 For the unstable distribution (sid) this problem has been fixed in version 1.4-1. We recommend that you update your mod-auth-shadow package.