The RSVPMaker plugin for WordPress is vulnerable to unauthenticated SQL Injection due to missing SQL escaping and parameterization on user supplied data passed to a SQL query in the rsvpmaker-api-endpoints.php file. This makes it possible for unauthenticated attackers to steal sensitive information from the database in versions up to and including 9.2.6.
The product constructs all or part of an SQL command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended SQL command when it is sent to a downstream component. Without sufficient removal or quoting of SQL syntax in user-controllable inputs, the generated SQL query can cause those inputs to be interpreted as SQL instead of ordinary user data.