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Squid CVE-2026-33515

| EUVDEUVD-2026-16067 MEDIUM
Out-of-bounds Read (CWE-125)
2026-03-26 GitHub_M
Buffer Overflow Information Disclosure Squid
6.9
CVSS 4.0 · GitHub Advisory
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Severity by source

GitHub Advisory PRIMARY
6.9 MEDIUM
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:L/SI:N/SA:N/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
Ubuntu
MEDIUM
qualitative
SUSE
7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Red Hat
5.3 MEDIUM
qualitative

Primary rating from GitHub Advisory.

CVSS VectorGitHub Advisory

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-2026-16067
Analysis Generated
Mar 26, 2026 - 01:00 vuln.today
CVE Published
Mar 26, 2026 - 00:13 nvd
MEDIUM 6.9

DescriptionGitHub Advisory

Squid is a caching proxy for the Web. Prior to version 7.5, due to improper input validation, Squid is vulnerable to out of bounds read when handling ICP traffic. This problem allows a remote attacker to receive small amounts of memory potentially containing sensitive information when responding with errors to invalid ICP requests. 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 prior to version 7.5 contains an out-of-bounds read vulnerability in ICP (Internet Cache Protocol) traffic handling due to improper input validation, classified as CWE-125. Remote attackers can exploit this to leak small amounts of process memory potentially containing sensitive information by sending malformed ICP requests to deployments with explicitly enabled ICP support (non-zero icp_port configuration). The vulnerability affects all versions of Squid before 7.5, and while no CVSS score or EPSS data is currently available, the information disclosure impact and remote attack vector indicate moderate to significant risk for affected deployments.

Technical ContextAI

The vulnerability exists in Squid's ICP protocol handler, which is a lightweight UDP-based protocol used for inter-cache communication in web caching hierarchies. ICP is an optional feature that must be explicitly enabled via the icp_port configuration parameter. The root cause is classified as CWE-125 (Out-of-bounds Read), indicating that Squid fails to properly validate the bounds of input data when processing ICP requests before performing memory reads. When an invalid or specially crafted ICP request is received, the validation bypass allows the application to read beyond allocated buffer boundaries, causing information disclosure. The affected product is identified via CPE cpe:2.3:a:squid-cache:squid with versions prior to 7.5, and notably, standard ACL-based mitigations (icp_access rules) cannot prevent this attack since the vulnerability exists in the parsing layer before access control evaluation.

RemediationAI

The primary remediation is to upgrade Squid to version 7.5 or later, which contains the patch for the out-of-bounds read vulnerability. Refer to the official Squid security advisory at https://github.com/squid-cache/squid/security/advisories/GHSA-84p4-hcx7-jj7c for vendor-specific upgrade guidance and patch details. For deployments that cannot immediately upgrade, the most effective interim mitigation is to disable ICP support entirely by setting icp_port to 0 in the Squid configuration file, as the vulnerability is only exploitable when ICP is explicitly enabled. Note that standard icp_access ACL rules cannot prevent exploitation, so disabling the protocol is the only workaround. Organizations should prioritize patching systems with ICP enabled, as these are directly at risk, while systems with ICP disabled are not vulnerable.

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Same weakness CWE-125 – Out-of-bounds Read

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8.8
CVE-2017-5030 HIGH POC
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CVE-2016-4523 HIGH
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CVE-2024-48456 HIGH POC
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CVE-2024-48457 HIGH POC
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Same technique Buffer Overflow

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CVE-2017-7269 CRITICAL POC
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CVE-2015-3113 CRITICAL POC
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CVE-2011-2462 CRITICAL POC
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CVE-2020-0796 CRITICAL POC
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CVE-2019-11043 CRITICAL POC
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CVE-2009-0927 HIGH POC
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CVE-2012-1889 HIGH POC
8.8

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 -

SUSE

Severity: High
Product Status
SUSE Linux Enterprise High Performance Computing 15 SP7 Fixed
SUSE Linux Enterprise Module for Server Applications 15 SP7 Fixed
SUSE Linux Enterprise Server 15 SP7 Fixed
SUSE Linux Enterprise Server 16.0 Fixed
SUSE Linux Enterprise Server 16.1 Fixed

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CVE-2026-33515 vulnerability details – vuln.today
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