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Rack provides an interface for developing web applications in Ruby. Prior to versions 2.2.11, 3.0.12, and 3.1.10, 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 3.1.10 contain a fix.
Cite this page
CVE-2025-25184. CVEDatabase.com. Retrieved 1 May 2026. https://cvedatabase.com/cve/CVE-2025-25184
Use CWE-93, Rack vendor hub and Rack product page to widen CVE-2025-25184 into its surrounding weakness, vendor, and product context.
Compare it with CVE-2026-34827, CVE-2026-34829 and CVE-2026-34785 for nearby disclosures in the same product family.