Privilege escalation in BeyondSEO lets contributors manage redirects

The Beyondseo plugin for WordPress is vulnerable to unauthorized access in versions up to, and including, 1.3.6. This is due to the plugin permanently granting the 'rankingcoach_write_redirectManager' (and sibling rankingcoach_write_* module capabilities) to the Contributor role via BaseModule::defineCapabilities(), whose default role list includes 'contributor', combined with the module's REST endpoints (registered through BaseSubmoduleApi::registerRouteCreate/registerRouteEdit/registerRouteDelete) authorizing state-changing requests solely through checkPermissionsPost(), which only calls current_user_can('rankingcoach_write_<module>') and performs no admin capability, ownership, or additional nonce check inside the callback. This makes it possible for authenticated attackers, with Contributor-level access and above, to elevate their privileges to effectively that of an Administrator with respect to site-wide redirect management — creating, updating, or deleting 301/302 redirects that RedirectManagerHooks::handleRedirects() executes for every frontend visitor on template_redirect, allowing hijacking of arbitrary paths (including /checkout, /wp-login.