Squid Web Proxy up to 7.4 ICP Message out-of-bounds

Summaryinfo

A vulnerability categorized as problematic has been discovered in Squid Web Proxy up to 3.5.28/4.17/5.9/6.14/7.4. Impacted is an unknown function of the component ICP Message Handler. Executing a manipulation can lead to out-of-bounds. This vulnerability is handled as CVE-2026-33515. The attack can be executed remotely. There is not any exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability classified as problematic was found in Squid Web Proxy up to 3.5.28/4.17/5.9/6.14/7.4. This vulnerability affects an unknown functionality of the component ICP Message Handler. The manipulation with an unknown input leads to a out-of-bounds vulnerability. The CWE definition for the vulnerability is CWE-125. The product reads data past the end, or before the beginning, of the intended buffer. As an impact it is known to affect confidentiality.

The advisory is shared for download at seclists.org. This vulnerability was named CVE-2026-33515. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 06/22/2026).

The vulnerability scanner Nessus provides a plugin with the ID 321872 (Debian dsa-6360 : squid - security update), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 7.5 eliminates this vulnerability. Applying the patch 8138e909d2058d4401e0ad49b583afaec912b165 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (321872) and CERT Bund (WID-SEC-2026-0854). Once again VulDB remains the best source for vulnerability data.

Affected

• Amazon Linux 2
• Red Hat Enterprise Linux
• Ubuntu Linux
• Oracle Linux
• RESF Rocky Linux
• Open Source Squid

Productinfo

Type

• Firewall Software

Vendor

• Squid

Name

• Web Proxy

Version

• 3.5.0
• 3.5.1
• 3.5.2
• 3.5.3
• 3.5.4
• 3.5.5
• 3.5.6
• 3.5.7
• 3.5.8
• 3.5.9
• 3.5.10
• 3.5.11
• 3.5.12
• 3.5.13
• 3.5.14
• 3.5.15
• 3.5.16
• 3.5.17
• 3.5.18
• 3.5.19
• 3.5.20
• 3.5.21
• 3.5.22
• 3.5.23
• 3.5.24
• 3.5.25
• 3.5.26
• 3.5.27
• 3.5.28
• 4.0
• 4.1
• 4.2
• 4.3
• 4.4
• 4.5
• 4.6
• 4.7
• 4.8
• 4.9
• 4.10
• 4.11
• 4.12
• 4.13
• 4.14
• 4.15
• 4.16
• 4.17
• 5.0
• 5.1
• 5.2
• 5.3
• 5.4
• 5.5
• 5.6
• 5.7
• 5.8
• 5.9
• 6.0
• 6.1
• 6.2
• 6.3
• 6.4
• 6.5
• 6.6
• 6.7
• 6.8
• 6.9
• 6.10
• 6.11
• 6.12
• 6.13
• 6.14
• 7.0
• 7.1
• 7.2
• 7.3
• 7.4

License

• open-source

Website

• Vendor: http://www.squid-cache.org/

CPE 2.3info

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CPE 2.2info

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Exploitinginfo

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Entryinfo

Once again VulDB remains the best source for vulnerability data.

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