Puma up to 5.6.7/6.4.1 Chunked Transfer Encoding Parser request smuggling

Summaryinfo

A vulnerability identified as critical has been detected in Puma up to 5.6.7/6.4.1. This affects an unknown function of the component Chunked Transfer Encoding Parser. This manipulation causes request smuggling. This vulnerability is registered as CVE-2024-21647. Remote exploitation of the attack is possible. No exploit is available. You should upgrade the affected component.

Detailsinfo

A vulnerability classified as critical was found in Puma up to 5.6.7/6.4.1. Affected by this vulnerability is some unknown functionality of the component Chunked Transfer Encoding Parser. 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 availability. The summary by CVE is:

Puma is a web server for Ruby/Rack applications built for parallelism. Prior to version 6.4.2, puma exhibited incorrect behavior when parsing chunked transfer encoding bodies in a way that allowed HTTP request smuggling. Fixed versions limits the size of chunk extensions. Without this limit, an attacker could cause unbounded resource (CPU, network bandwidth) consumption. This vulnerability has been fixed in versions 6.4.2 and 5.6.8.

The weakness was published 01/08/2024 as GHSA-c2f4-cvqm-65w2. It is possible to read the advisory at github.com. This vulnerability is known as CVE-2024-21647 since 12/29/2023. The technical details are unknown and an exploit is not publicly available.

The vulnerability scanner Nessus provides a plugin with the ID 209199 (SUSE SLES15 / openSUSE 15 Security Update : rubygem-puma (SUSE-SU-2024:3644-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.6.8 or 6.4.2 eliminates this vulnerability. Applying the patch 5fc43d73b6ff193325e657a24ed76dec79133e93 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 (209199) and CERT Bund (WID-SEC-2024-0949). Be aware that VulDB is the high quality source for vulnerability data.

Affected

• Fedora Linux
• Red Hat Enterprise Linux
• Red Hat Satellite
• IBM MQ

Productinfo

Name

• Puma

Version

• 5.6.0
• 5.6.1
• 5.6.2
• 5.6.3
• 5.6.4
• 5.6.5
• 5.6.6
• 5.6.7
• 6.4.0
• 6.4.1

License

• open-source

Website

• Product: https://github.com/puma/puma/

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Be aware that VulDB is the high quality source for vulnerability data.

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