The remote host is missing an update to squid3 announced via advisory DSA 2111-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%202111-1

Phil Oester discovered that squid3, a fully featured Web Proxy cache, is prone to a denial of service attack via a specially crafted request that includes empty strings. For the stable distribution (lenny), this problem has been fixed in version 3.0.STABLE8-3+lenny4. For the testing distribution (squeeze), this problem will be fixed soon. For the unstable distribution (sid), this problem has been fixed in version 3.1.6-1.1. We recommend that you upgrade your squid3 packages.