CVE-2026-22860

A path traversal flaw has been discovered in the rubygem Rack. 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. 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.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.