WordPress JSON API Auth Plugin Authentication Bypass via Cookie Disclosure

The JSON API Auth plugin for WordPress is vulnerable to an authentication bypass via cached session cookie disclosure in all versions up to and including 3.1.2.

The required PI-Media/json-api parent plugin caches controller dispatch results in transients keyed solely by URI and query string, ignoring HTTP method and POST body. As a result, the generate_auth_cookie() endpoint, which embeds a live WordPress logged_in cookie produced by wp_generate_auth_cookie() directly in its JSON response body, can serve that cached authenticated response to any subsequent unauthenticated GET request to the same URI.

This lets unauthenticated attackers retrieve a valid Administrator logged_in session cookie from the cached response and use it to fully authenticate as the site Administrator, including via the same plugin's get_currentuserinfo endpoint and any cookie-authenticated controller action.

• Affected versions: all versions up to and including 3.1.2.
• Preconditions: PI-Media/json-api parent plugin installed and active with the Auth controller enabled; a legitimate Administrator must have POSTed to /api/auth/generate_auth_cookie/ within the preceding 24-hour cache TTL.
• The nominal HTTPS enforcement gate in Auth.php is trivially bypassed by supplying insecure=cool as a request parameter.