CVE-2026-78006

The Events Calendar WordPress plugin is vulnerable to unauthenticated remote code execution (CWE-502, unsafe deserialization) in all versions up to and including 6.17.4 via the is_safe_widget_instance function, whose protection can be bypassed because PHP fires magic methods during pre-parse while enable_rendering_widget_copied() forges a valid wp_hash integrity attribute before unserialize() is reached. The flaw is reachable without authentication or approval because the plugin's V2 single-event template runs do_blocks() over buffered comment HTML, and WordPress returns a moderation-hash URL that lets an unauthenticated commenter immediately view their own still-pending comment, delivering attacker-injected block markup to the vulnerable code path before moderation occurs. Successful exploitation gives an unauthenticated attacker arbitrary code execution on the web server with full confidentiality, integrity, and availability impact. Any site running a vulnerable version is affected, but only when comments are enabled and visible on events. No public proof-of-concept is known, the issue is not in CISA's KEV catalog, and no in-the-wild exploitation has been confirmed.

What to do: Update The Events Calendar to the latest available release (any version newer than 6.17.4) as soon as possible. Until patched, disable comments on events or prevent them from being publicly visible, since exploitation requires comments to be enabled and viewable on event pages. Review logs for pending comments submitted to events and unexpected widget/serialized data, and treat comment moderation queues on event posts with suspicion.