The Old Posts Highlighter plugin for WordPress is vulnerable to Cross-Site Request Forgery in all versions up to, and including, 1.0.3. This is due to missing or incorrect nonce validation on the OPH_options function. This makes it possible for unauthenticated attackers to update the plugin's configuration settings without authorization via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.
CWE-352