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Squid CVE-2026-33526

| EUVD-2026-16068 CRITICAL
Use After Free (CWE-416)
2026-03-26 GitHub_M
9.2
CVSS 4.0
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CVSS VectorNVD

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:X/V:X/RE:X/U:X
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
X

Lifecycle Timeline

4
Patch released
Mar 31, 2026 - 21:13 nvd
Patch available
EUVD ID Assigned
Mar 26, 2026 - 01:00 euvd
EUVD-2026-16068
Analysis Generated
Mar 26, 2026 - 01:00 vuln.today
CVE Published
Mar 26, 2026 - 00:16 nvd
CRITICAL 9.2

DescriptionNVD

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.

AnalysisAI

Squid versions prior to 7.5 contain a heap use-after-free vulnerability (CWE-416) in ICP (Internet Cache Protocol) traffic handling that enables remote attackers to reliably trigger denial of service against affected proxy services. The vulnerability affects any Squid deployment with ICP support explicitly enabled via non-zero icp_port configuration, and cannot be mitigated through access control rules alone. …

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RemediationAI

Within 24 hours: Identify all affected systems and apply vendor patches immediately. If patching is delayed, consider network segmentation to limit exposure.

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Vendor StatusVendor

Ubuntu

Priority: Medium
squid
Release Status Version
focal needs-triage -
jammy needs-triage -
noble needs-triage -
questing needs-triage -
upstream needs-triage -
squid3
Release Status Version
xenial needs-triage -
bionic needs-triage -
jammy DNE -
noble DNE -
questing DNE -
upstream needs-triage -

Debian

squid
Release Status Fixed Version Urgency
bullseye vulnerable 4.13-10+deb11u3 -
bullseye (security) vulnerable 4.13-10+deb11u6 -
bookworm vulnerable 5.7-2+deb12u5 -
bookworm (security) vulnerable 5.7-2+deb12u4 -
trixie, trixie (security) vulnerable 6.13-2+deb13u1 -
forky vulnerable 7.4-1 -
sid fixed 7.5-1 -
(unstable) fixed 7.5-1 -

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CVE-2026-33526 vulnerability details – vuln.today

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