Affected: joedolson My Calendar - Accessible Event Manager

My Calendar WordPress plugin 3.8.8 before 3.8.11 contains a shortcode injection vulnerability that allows unauthenticated attackers to execute registered shortcodes via the mcs search parameter. The mcs value reaches mc_search_results() in src/my-calendar-search.php without bracket encoding before do_shortcode runs, so a GET request triggers shortcodes on any page or post, enabling content injection and spoofing.