rack up to 2.2.10/3.0.11/3.1.10 Rack::CommonLogger env['REMOTE_USER'] crlf injection

Summaryinfo

A vulnerability, which was classified as problematic, has been found in rack up to 2.2.10/3.0.11/3.1.10. The impacted element is the function Rack::CommonLogger. This manipulation of the argument env['REMOTE_USER'] causes crlf injection. This vulnerability is registered as CVE-2025-25184. Remote exploitation of the attack is possible. No exploit is available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability has been found in rack up to 2.2.10/3.0.11/3.1.10 and classified as problematic. Affected by this vulnerability is the function Rack::CommonLogger. The manipulation of the argument env['REMOTE_USER'] with an unknown input leads to a crlf injection vulnerability. The CWE definition for the vulnerability is CWE-93. The product uses CRLF (carriage return line feeds) as a special element, e.g. to separate lines or records, but it does not neutralize or incorrectly neutralizes CRLF sequences from inputs. As an impact it is known to affect integrity. The summary by CVE is:

Rack provides an interface for developing web applications in Ruby. Prior to versions 2.2.11, 3.0.12, and 3.1.11, Rack::CommonLogger can be exploited by crafting input that includes newline characters to manipulate log entries. The supplied proof-of-concept demonstrates injecting malicious content into logs. When a user provides the authorization credentials via Rack::Auth::Basic, if success, the username will be put in env['REMOTE_USER'] and later be used by Rack::CommonLogger for logging purposes. The issue occurs when a server intentionally or unintentionally allows a user creation with the username contain CRLF and white space characters, or the server just want to log every login attempts. If an attacker enters a username with CRLF character, the logger will log the malicious username with CRLF characters into the logfile. Attackers can break log formats or insert fraudulent entries, potentially obscuring real activity or injecting malicious data into log files. Versions 2.2.11, 3.0.12, and 3.1.11 contain a fix.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2025-25184 since 02/03/2025. The exploitation appears to be easy. The attack can be launched remotely. Technical details of the vulnerability are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 230824 (Linux Distros Unpatched Vulnerability : CVE-2025-25184), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 2.2.11, 3.0.12 or 3.1.11 eliminates this vulnerability. Applying the patch 074ae244430cda05c27ca91cda699709cfb3ad8e 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 vulnerability database at Tenable (230824). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Name

• rack

Version

• 2.2.0
• 2.2.1
• 2.2.2
• 2.2.3
• 2.2.4
• 2.2.5
• 2.2.6
• 2.2.7
• 2.2.8
• 2.2.9
• 2.2.10
• 3.0.0
• 3.0.1
• 3.0.2
• 3.0.3
• 3.0.4
• 3.0.5
• 3.0.6
• 3.0.7
• 3.0.8
• 3.0.9
• 3.0.10
• 3.0.11
• 3.1.0
• 3.1.1
• 3.1.2
• 3.1.3
• 3.1.4
• 3.1.5
• 3.1.6
• 3.1.7
• 3.1.8
• 3.1.9
• 3.1.10

License

• open-source

Website

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

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Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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