The remote host is missing an update to squid announced via advisory DSA 721-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%20721-1

Michael Bhola discovered a bug in Squid, the popular WWW proxy cache. Squid does not trigger a fatal error when it identifies missing or invalid ACLs in the http_access configuration, which could lead to less restrictive ACLs than intended by the administrator. For the stable distribution (woody) this problem has been fixed in version 2.4.6-2woody8. For the unstable distribution (sid) this problem has been fixed in version 2.5.9-7. We recommend that you upgrade your squid packages.