CVE-2026-13400
Simply Schedule Appointments < 1.6.12.4 - Unauthenticated Stored XSS via Booking Customer Information
MEDIUM 6.1EPSS 0.3%
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
- Simply Schedule Appointments
- CVSS v3.1 CNA
- 6.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N - EPSS
- 0.25% chance of exploitation in the next 30 days, 16th percentile
- Published
- 2026-07-27