CVE-2026-33526 CRITICAL

CVE-2026-33526: Squid vulnerable to Denial of Service in ICP Request handling

Vendor Squid-Cache
Product squid
Weakness CWE-416
Published March 26, 2026
Last update June 30, 2026

CVSS base score

9.2/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality
Integrity

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

March 26, 2026 CVE published
June 30, 2026 Record updated