Canonical ruby webrick up to 1.9.2 request smuggling

Summaryinfo

A vulnerability was found in Canonical ruby webrick up to 1.9.2. It has been rated as problematic. This impacts an unknown function. This manipulation causes request smuggling. This vulnerability appears as CVE-2026-38969. The attack may be initiated remotely. There is no available exploit. It is suggested to install a patch to address this issue.

Detailsinfo

A vulnerability has been found in Canonical ruby webrick up to 1.9.2 and classified as problematic. Affected by this vulnerability is an unknown function. The manipulation 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 integrity. The summary by CVE is:

ruby webrick through v1.9.2 WEBrick reparses trailer Content-Length into canonical request state, enabling request smuggling. NOTE: the Supplier reports that "The project README states that it is suitable for testing and development, and that its developers do not encourage its use to serve production web applications that may be subject to hostile input. It is not a production web server and is not intended to receive traffic from untrusted sources. Request smuggling is only reachable when WEBrick sits behind a proxy and receives hostile traffic in a production deployment, which is the configuration the project documents as discouraged."

The advisory is shared at github.com. This vulnerability is known as CVE-2026-38969 since 04/06/2026. The exploitation appears to be easy. The attack can be launched remotely. Neither technical details nor an exploit are publicly available.

The vulnerability scanner Nessus provides a plugin with the ID 325070 (Linux Distros Unpatched Vulnerability : CVE-2026-38969), which helps to determine the existence of the flaw in a target environment.

Applying a patch is able to eliminate this problem. The bugfix is ready for download at github.com.

The vulnerability is also documented in the vulnerability database at Tenable (325070). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Type

• Programming Language Software

Vendor

• Canonical

Name

• ruby webrick

Version

• 1.9.0
• 1.9.1
• 1.9.2

License

• open-source

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CPE 2.2info

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Entryinfo

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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