Puma Gem up to 3.12.1/4.3.1 on Ruby Header HTTP Response response splitting

Summaryinfo

A vulnerability labeled as critical has been found in Puma Gem up to 3.12.1/4.3.1 on Ruby. This issue affects some unknown processing of the component Header Handler. Executing a manipulation as part of HTTP Response can lead to response splitting. This vulnerability appears as CVE-2020-5247. The attack may be performed from remote. There is no available exploit. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in Puma Gem up to 3.12.1/4.3.1 on Ruby (Ruby Gem). It has been declared as critical. This vulnerability affects an unknown part of the component Header Handler. The manipulation as part of a HTTP Response leads to a response splitting vulnerability. The CWE definition for the vulnerability is CWE-113. The product receives data from an HTTP agent/component (e.g., web server, proxy, browser, etc.), but it does not neutralize or incorrectly neutralizes CR and LF characters before the data is included in outgoing HTTP headers. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

In Puma (RubyGem) before 4.3.2 and 3.12.2, if an application using Puma allows untrusted input in a response header, an attacker can use newline characters (i.e. `CR`, `LF` or`/r`, `/n`) to end the header and inject malicious content, such as additional headers or an entirely new response body. This vulnerability is known as HTTP Response Splitting. While not an attack in itself, response splitting is a vector for several other attacks, such as cross-site scripting (XSS). This is related to CVE-2019-16254, which fixed this vulnerability for the WEBrick Ruby web server. This has been fixed in versions 4.3.2 and 3.12.3 by checking all headers for line endings and rejecting headers with those characters.

The weakness was presented 02/28/2020 (GitHub Repository). The advisory is shared for download at github.com. This vulnerability was named CVE-2020-5247 since 01/02/2020. The attack can be initiated remotely. A single authentication is necessary for exploitation. Successful exploitation requires user interaction by the victim. There are neither technical details nor an exploit publicly available.

Upgrading to version 3.12.2 or 4.3.2 eliminates this vulnerability.

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Productinfo

Type

• Ruby Gem

Name

• Puma Gem

Version

• 3.12.0
• 3.12.1
• 4.3.0
• 4.3.1

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Once again VulDB remains the best source for vulnerability data.

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