CVE-2025-46727

Name of the Vulnerable Software and Affected Versions Rack versions prior to 2.2.14, 3.0.16, and 3.1.14

Description Rack is a modular Ruby web server interface. The Rack::QueryParser parses query strings and application/x-www-form-urlencoded bodies into Ruby data structures without imposing any limit on the number of parameters, allowing attackers to send requests with extremely large numbers of parameters. This allows an attacker to send a single request containing hundreds of thousands (or more) of parameters, which consumes excessive memory and CPU during parsing. An attacker can trigger denial of service by sending specifically crafted HTTP requests, which can cause memory exhaustion or pin CPU resources, stalling or crashing the Rack server. This results in full service disruption until the affected worker is restarted.

Recommendations To resolve the issue, update to a version of Rack that limits the number of parameters parsed, such as version 2.2.14, 3.0.16, or 3.1.14. Alternatively, use middleware to enforce a maximum query string size or parameter count. Employ a reverse proxy (such as Nginx) to limit request sizes and reject oversized query strings or bodies. Limiting request body sizes and query string lengths at the web server or CDN level is an effective mitigation.