Modern Events Calendar Lite < 5.22.1 - Admin+ Stored Cross-Site Scripting

Reaching this weakness in Modern Events Calendar Lite <= 5.22.1 takes a caller who can reach the endpoint. Cross-site scripting happens when input from a request is written into a page without being escaped for the context it lands in, so the browser parses attacker-supplied text as markup or script.

Injected script runs with the privileges of whoever views the affected page, which is how these flaws turn into administrator session theft, silent account creation or persistent backdoors in page content. For Modern Events Calendar Lite the fix is 5.22.2: builds <= 5.22.1 are affected, anything from 5.22.2 onward is not.