The remote Debian host is missing a security-related update.
Squid3, a fully featured Web proxy cache, is prone to a denial of service attack due to memory consumption caused by memory leaks in cachemgr.cgi : - CVE-2012-5643 squid's cachemgr.cgi was vulnerable to excessive resource use. A remote attacker could exploit this flaw to perform a denial of service attack on the server and other hosted services. - CVE-2013-0189 The original patch for CVE-2012-5643 was incomplete. A remote attacker still could exploit this flaw to perform a denial of service attack.
Upgrade the squid3 packages. For the stable distribution (squeeze), these problems have been fixed in version 3.1.6-1.2+squeeze3.