National Science Foundation » Squid Web Proxy Cache : Security Vulnerabilities, CVEs,

Squid Web Proxy Cache 2.3.STABLE5 allows remote attackers to bypass security controls and access arbitrary websites via "@@" sequences in a URL within Internet Explorer.

Squid Web Proxy Cache 2.5 might allow remote attackers to obtain sensitive information via URLs containing invalid hostnames that cause DNS operations to fail, which results in references to previously used error messages.

Buffer overflow in the ntlm_check_auth (NTLM authentication) function for Squid Web Proxy Cache 2.5.x and 3.x, when compiled with NTLM handlers enabled, allows remote attackers to execute arbitrary code via a long password ("pass" variable).