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.

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.

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.