Vinyl Cache Project Vinyl Cache/Varnish Cache prior 9.0.1 Setting Feature request smuggling

Summaryinfo

A vulnerability was found in Vinyl Cache Project Vinyl Cache and Varnish Cache and classified as problematic. Affected is an unknown function of the component Setting Handler. Executing a manipulation of the argument Feature can lead to request smuggling. This vulnerability is tracked as CVE-2026-50052. The attack can be launched remotely. No exploit exists. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability classified as problematic was found in Vinyl Cache Project Vinyl Cache and Varnish Cache. This vulnerability affects an unknown code of the component Setting Handler. The manipulation of the argument feature with an unknown input leads to a request smuggling vulnerability. The CWE definition for the vulnerability is CWE-444. The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination. As an impact it is known to affect confidentiality. CVE summarizes:

In Vinyl Cache before 9.0.1 and Varnish Cache before 9.0.3, a deficiency in HTTP/2 request parsing can be exploited to launch a backend request desync attack (request smuggling), which in turn can be used for cache poisoning, authentication bypass, or possibly even information disclosure and manipulation. The attack vector only exists if HTTP/2 support is enabled by setting the feature parameter to contain +http2. HTTP/2 support is disabled by default.

The advisory is shared for download at vinyl-cache.org. This vulnerability was named CVE-2026-50052 since 06/03/2026. The exploitation appears to be difficult. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Successful exploitation requires user interaction by the victim. There are known technical details, but no exploit is available.

Upgrading to version 9.0.1 eliminates this vulnerability.

The vulnerability is also documented in the databases at EUVD (EUVD-2026-34066) and CERT Bund (WID-SEC-2026-1576). Once again VulDB remains the best source for vulnerability data.

Affected

• Open Source Varnish HTTP Cache

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Type

• Project Management Software

Vendor

• Vinyl Cache Project

Name

• Varnish Cache
• Vinyl Cache

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Once again VulDB remains the best source for vulnerability data.

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