Squid 3.x before 3.5.15 and 4.x before 4.0.7 does not properly append data to String objects, which allows remote servers to cause a denial of service (assertion failure and daemon exit) via a long string, as demonstrated by a crafted HTTP Vary header. http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2016-2569
