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Vulnerability · Published Mar 26, 2026 · Assigned by GitHub_M

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

High 7.5

In plain English

A high-severity use-after-free in squid from squid-cache. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 9.1% (higher than 95% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.5High
Exploit odds (30 days)9.1%top 4.7% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
AlmaLinux:8libecap1.0.1-2.module_el8.6.0+3048+383bc947ALSA-2026:8317
AlmaLinux:8libecap1.0.1-2.module_el8.6.0+2741+01592ae8ALSA-2026:8317
AlmaLinux:8libecap-devel1.0.1-2.module_el8.6.0+2741+01592ae8ALSA-2026:8317
AlmaLinux:8libecap-devel1.0.1-2.module_el8.6.0+3048+383bc947ALSA-2026:8317
AlmaLinux:10squid7:6.10-6.el10_1.3ALSA-2026:8119
AlmaLinux:8squid7:4.15-10.module_el8.10.0+4163+e77fcdac.11ALSA-2026:8317
AlmaLinux:9squid7:5.5-22.el9_7.4ALSA-2026:6301
Debian:12squid5.7-2+deb12u6DEBIAN-CVE-2026-33526
Debian:13squid6.13-2+deb13u2DEBIAN-CVE-2026-33526
Debian:14squid7.5-1DEBIAN-CVE-2026-33526
Rocky Linux:8libecap0:1.0.1-2.module+el8.9.0+1437+df5ea8f0RLSA-2026:8317
Rocky Linux:10squid7:6.10-6.el10_1.3RLSA-2026:8119
Rocky Linux:8squid7:4.15-10.module+el8.10.0+1885+e30b7122.3RLSA-2026:8317
Rocky Linux:8squid7:4.15-10.module+el8.10.0+1928+e8441768.5RLSA-2026:8317
Rocky Linux:8squid7:4.15-10.module+el8.10.0+1985+eaf982f0.6RLSA-2026:8317
Rocky Linux:8squid7:4.15-10.module+el8.10.0+2080+49064dbd.9RLSA-2026:8317
Rocky Linux:8squid7:4.15-10.module+el8.10.0+1758+80ba9f4bRLSA-2026:8317
Rocky Linux:8squid7:4.15-10.module+el8.10.0+1881+7e31fb44.1RLSA-2026:8317
Rocky Linux:9squid7:5.5-22.el9_7.4RLSA-2026:6301
Ubuntu:22.04:LTSsquid5.9-0ubuntu0.22.04.8USN-8941-1
Ubuntu:22.04:LTSsquid5.9-0ubuntu0.22.04.5UBUNTU-CVE-2026-33526
Ubuntu:24.04:LTSsquid6.14-0ubuntu0.24.04.5USN-8941-1
Ubuntu:24.04:LTSsquid6.14-0ubuntu0.24.04.2UBUNTU-CVE-2026-33526
Ubuntu:25.10squid6.14-0ubuntu0.25.10.2UBUNTU-CVE-2026-33526

Affected products (as reported)

VendorProductVersions
squid-cache squid < 7.5

Weakness: CWE-416, CWE-826, CWE-825 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References