The Corner Ad plugin for WordPress is vulnerable to Cross-Site Request Forgery in versions up to, and including, 1.0.56. This is due to missing or incorrect nonce validation on its corner_ad_settings_page function. This makes it possible for unauthenticated attackers to trigger the deletion of ads via forged request granted they can trick a site administrator into performing an action such as clicking on a link.
https://www.wordfence.com/threat-intel/vulnerabilities/id/0a6c5e9a-754f-41c8-b27b-caa133b5070f
https://plugins.trac.wordpress.org/browser/corner-ad/trunk/corner-ad.php?rev=2782613#L240