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CVE-2026-13400mediumCWE-79

Simply Schedule Appointments < 1.6.12.4 - Unauthenticated Stored XSS via Booking Customer Information

33Vexday Risk Score

No sign of exploitation. It has a public proof of concept.

ssvc Attendcvss 6.1epss 0.1%
exploitation probability
0.1%top 95% of all CVEs
observed exploitation
nono source reports it
1 public exploit(s)
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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
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