The Fense Proxy & VPN Blocker plugin for WordPress is vulnerable to unauthorized modification of data due to a missing capability check and missing nonce validation on the fense_bpvt_save_settings() function in versions up to, and including, 3.0.1. The callback is registered to both wp_ajax_* and wp_ajax_nopriv_* hooks and unconditionally calls delete_option() on four plugin options and delete_transient() on three transients tied to the plugin's API key cache and settings. This makes it possible for unauthenticated attackers to delete plugin options and transients, effectively resetting the plugin's API key/data cache and forcing the plugin to refetch state.
Analyzing vulnerability vectors…