CVE-2026-13400
Medium
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.
SeverityMedium
CVSS6.1
Exploit probability—
ProductSimply Schedule Appointments
PublishedJul 27, 2026
First seenJul 27, 2026
Weakness typeCWE-79Cross-site scripting (XSS)
How to fix
Update
- Simply Schedule Appointments1.6.12.4 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| Simply Schedule Appointments | v < 1.6.12.4 | 1.6.12.4 |
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