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.
Weakness
The product parses a formatted message or structure, but it does not handle or incorrectly handles a length field that is inconsistent with the actual length of the associated data.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Rack | Rack | * | 2.2.23 (excluding) |
| Rack | Rack | 3.0.0 (including) | 3.1.21 (excluding) |
| Rack | Rack | 3.2.0 (including) | 3.2.6 (excluding) |
| Ruby-rack | Ubuntu | devel | * |
| Ruby-rack | Ubuntu | esm-apps/jammy | * |
| Ruby-rack | Ubuntu | jammy | * |
| Ruby-rack | Ubuntu | noble | * |
| Ruby-rack | Ubuntu | questing | * |
| Ruby-rack | Ubuntu | resolute | * |