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Vulnerability record · CVE-2026-33526 · published 26 March 2026

CVE-2026-33526: Squid-cache squid use after free vulnerability

Squid Cache · Squid

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.

9.2 CVSS 4.0 Critical EPSS 13% · top 3.8% CWE-416 · Use after freeCWE-826 · CWE-826
9.2CVSS 4.0 base score
13%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
18References
15 Jul 2026Last modified by NVD

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.

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/squid-cache/squid/commit/8a7d42f9d44befb8fcbbb619505587c8de6a1e91 Patch
https://github.com/squid-cache/squid/security/advisories/GHSA-hpfx-h48q-gvwg Vendor Advisory
http://www.openwall.com/lists/oss-security/2026/03/25/2 Third Party Advisory
https://access.redhat.com/errata/RHSA-2026:10255
https://access.redhat.com/errata/RHSA-2026:10256
https://access.redhat.com/errata/RHSA-2026:10257
https://access.redhat.com/errata/RHSA-2026:11901
https://access.redhat.com/errata/RHSA-2026:20564
https://access.redhat.com/errata/RHSA-2026:20565
https://access.redhat.com/errata/RHSA-2026:20580
https://access.redhat.com/errata/RHSA-2026:6301
https://access.redhat.com/errata/RHSA-2026:8119
https://access.redhat.com/errata/RHSA-2026:8317
https://access.redhat.com/errata/RHSA-2026:8880
https://access.redhat.com/errata/RHSA-2026:9220
https://access.redhat.com/security/cve/CVE-2026-33526
https://bugzilla.redhat.com/show_bug.cgi?id=2451574
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33526.json

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-33526), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.