Squid caching proxy versions prior to 7.5 contain a use-after-free vulnerability in ICP traffic handling that allows remote attackers to perform reliable denial of service attacks. The vulnerability stems from premature resource release during expected lifetime and heap use-after-free bugs. The attack specifically targets Squid deployments with ICP support enabled (non-zero icp_port configuration). Standard mitigation through icp_access rules is ineffective against this vulnerability. The issue has been resolved in Squid version 7.5.