The Freemius SDK, as used by hundreds of WordPress plugin and theme developers, was vulnerable to Cross-Site Request Forgery and Information disclosure due to missing capability checks and nonce protection on the _get_debug_log, _get_db_option, and the _set_db_option functions in versions up to, and including 2.4.2. Any WordPress plugin or theme running a version of Freemius less than 2.4.3 is vulnerable.

The Event Registration Calendar By vcita plugin, versions up to and including 3.9.1, and Online Payments – Get Paid with PayPal, Square & Stripe plugin, for WordPress are vulnerable to Cross-Site Request Forgery. This is due to missing nonce validation in the ls_parse_vcita_callback() function. This makes it possible for unauthenticated attackers to modify the plugin's settings and inject malicious JavaScript via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.

The Event Registration Calendar By vcita plugin, versions up to and including 3.9.1, and Online Payments – Get Paid with PayPal, Square & Stripe plugin, for WordPress are vulnerable to Stored Cross-Site Scripting via the 'email' parameter in versions up to, and including, 1.3.1 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers with the edit_posts capability, such as contributors and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.

Cross-site scripting (XSS) vulnerability in Event Registration allows remote attackers to inject arbitrary web script or HTML via the (1) event_id parameter to view-event-details.php or (2) select_events parameter to event-registration.php. NOTE: the provenance of this information is unknown; the details are obtained from third party information.