The WP Maps - Google Maps,OpenStreetMap,Mapbox,Store Locator,Listing,Directory & Filters plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'location_messages' parameter in all versions up to, and including, 4.9.4 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with administrator-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. Exploitation requires the attacker to hold the custom wpgmp_manage_location capability, which is granted to administrators by default but can be assigned to lower-privileged roles via the plugin's Permissions screen.