CVE-2026-22860

Rack is a modular Ruby web server interface. Prior to versions 2.2.22, 3.1.20, and 3.2.5, `Rack::Directory`’s path check used a string prefix match on the expanded path. A request like `/../root_example/` can escape the configured root if the target path starts with the root string, allowing directory listing outside the intended root. Versions 2.2.22, 3.1.20, and 3.2.5 fix the issue.

Rack is a modular Ruby web server interface. Prior to versions 2.2.22, 3.1.20, and 3.2.5, `Rack::Directory`’s path check used a string prefix match on the expanded path. A request like `/../root_example/` can escape the configured root if the target path starts with the root string, allowing directory listing outside the intended root. Versions 2.2.22, 3.1.20, and 3.2.5 fix the issue.

## Summary `Rack::Directory`’s path check used a string prefix match on the expanded path. A request like `/../root_example/` can escape the configured root if the target path starts with the root string, allowing directory listing outside the intended root. ## Details In `directory.rb`, `File.expand_path(File.join(root, path_info)).start_with?(root)` does not enforce a path boundary. If the server root is `/var/www/root`, a path like `/var/www/root_backup` passes the check because it shares the same prefix, so `Rack::Directory` will list that directory also. ## Impact Information disclosure via directory listing outside the configured root when `Rack::Directory` is exposed to untrusted clients and a directory shares the root prefix (e.g., `public2`, `www_backup`). ## Mitigation * Update to a patched version of Rack that correctly checks the root prefix. * Don't name directories with the same prefix as one which is exposed via `Rack::Directory`.

## Summary `Rack::Directory`’s path check used a string prefix match on the expanded path. A request like `/../root_example/` can escape the configured root if the target path starts with the root string, allowing directory listing outside the intended root. ## Details In `directory.rb`, `File.expand_path(File.join(root, path_info)).start_with?(root)` does not enforce a path boundary. If the server root is `/var/www/root`, a path like `/var/www/root_backup` passes the check because it shares the same prefix, so `Rack::Directory` will list that directory also. ## Impact Information disclosure via directory listing outside the configured root when `Rack::Directory` is exposed to untrusted clients and a directory shares the root prefix (e.g., `public2`, `www_backup`). ## Mitigation * Update to a patched version of Rack that correctly checks the root prefix. * Don't name directories with the same prefix as one which is exposed via `Rack::Directory`.

Rack es una interfaz modular de servidor web Ruby. Antes de las versiones 2.2.22, 3.1.20 y 3.2.5, la verificación de ruta de 'Rack::Directory' utilizaba una coincidencia de prefijo de cadena en la ruta expandida. Una solicitud como '/../root_example/' puede escapar de la raíz configurada si la ruta de destino comienza con la cadena raíz, permitiendo la enumeración de directorios fuera de la raíz prevista. Las versiones 2.2.22, 3.1.20 y 3.2.5 solucionan el problema.