The remote host is missing an update to squid/squid3 announced via advisory DSA 1991-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%201991-1

Two denial of service vulnerabilities have been discovered in squid and squid3, a web proxy. The Common Vulnerabilities and Exposures project identifies the following problems: CVE-2009-2855 Bastian Blank discovered that it is possible to cause a denial of service via a crafted auth header with certain comma delimiters. CVE-2010-0308 Tomas Hoger discovered that it is possible to cause a denial of service via invalid DNS header-only packets. For the stable distribution (lenny), these problems have been fixed in version 2.7.STABLE3-4.1lenny1 of the squid package and version 3.0.STABLE8-3+lenny3 of the squid3 package. For the oldstable distribution (etch), these problems have been fixed in version 2.6.5-6etch5 of the squid package and version 3.0.PRE5-5+etch2 of the squid3 package. For the testing distribution (squeeze) and the unstable distribution (sid), these problems will be fixed soon. We recommend that you upgrade your squid/squid3 packages.