Description
Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Files#fail sets the Content-Length response header using String#size instead of String#bytesize. When the response body contains multibyte UTF-8 characters, the declared Content-Length is smaller than the number of bytes actually sent on the wire. Because Rack::Files reflects the requested path in 404 responses, an attacker can trigger this mismatch by requesting a non-existent path containing percent-encoded UTF-8 characters. This results in incorrect HTTP response framing and may cause response desynchronization in deployments that rely on the incorrect Content-Length value. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.
Problem types
CWE-130: Improper Handling of Length Parameter Inconsistency
CWE-135: Incorrect Calculation of Multi-Byte String Length
Product status
>= 3.0.0.beta1, < 3.1.21
>= 3.2.0, < 3.2.6
References
github.com/rack/rack/security/advisories/GHSA-q2ww-5357-x388