Appointment Booking Calendar — Simply Schedule Appointments Booking Plugin, CVE-2026-104000

CVE, Research URL: CVE-2026-104000
Home page URL: Security reports for Appointment Booking Calendar — Simply Schedule Appointments Booking Plugin
Application: Appointment Booking Calendar — Simply Schedule Appointments Booking Plugin
Published on: Oct 16, 2026
Research Description: The Simply Schedule Appointments plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'status' parameter in all versions up to, and including, 1.6.12.35 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The malicious payload is stored unconditionally because debug logging is enabled by default, and the debug-log viewer is accessible to anyone holding the site-wide Support PIN (an HMAC-MD5 of AUTH_SALT displayed in wp-admin), meaning the injected script will execute against the administrator's session during ordinary support or troubleshooting workflows.
Affected versions: max 1.6.12.37.
Status: vulnerable