CVE-2026-33526
HighCVSS 7.5Exploitation Probability (EPSS)
Very high risk95th percentile - higher than 95% of all known CVEs
Summary
Squid versions prior to 7.5 contain a heap Use-After-Free vulnerability in ICP traffic handling, allowing a remote attacker to perform a reliable and repeatable Denial of Service attack. The attack requires ICP support enabled (non-zero `icp_port`) and cannot be mitigated by `icp_access` rules.
Risk Assessment
Organizations using a vulnerable Squid version with ICP enabled risk service disruption from a remote attacker, potentially leading to unavailability of network resources.
Recommendation
Immediately upgrade Squid to version 7.5 or later. If upgrading is not possible, disable ICP support by setting `icp_port 0` if acceptable for the environment.
Original NVD description (English source)
Squid is a caching proxy for the Web. Prior to version 7.5, due to heap Use-After-Free, Squid is vulnerable to Denial of Service when handling ICP traffic. This problem allows a remote attacker to perform a reliable and repeatable Denial of Service attack against the Squid service using ICP protocol. This attack is limited to Squid deployments that explicitly enable ICP support (i.e. configure non-zero `icp_port`). This problem _cannot_ be mitigated by denying ICP queries using `icp_access` rules. Version 7.5 contains a patch.