Appointment Booking Calendar — Simply Schedule Appointments Booking Plugin, CVE-2026-13400
- CVE, Research URL
- Home page URL
-
Security reports for Appointment Booking Calendar — Simply Schedule Appointments Booking Plugin
- Published on
- Jul 27, 2026
- Research Description
- Simply Schedule Appointments is vulnerable to unauthenticated Stored Cross-Site Scripting in all versions up to and including 1.6.12.2. The root cause is a sanitization-ordering defect: the rendered notification content is decoded back into live HTML after it has already passed through the Simply Schedule Appointments WordPress plugin before 1.6.12.4's wp_kses_post() filter, so a double-encoded payload survives intake and is reintroduced as an executable element at render time.
- Affected versions
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max 1.6.12.4.
- Status
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vulnerable