CVE-2026-13400
MEDIUMSimply Schedule Appointments < 1.6.12.4 - Unauthenticated Stored XSS via Booking Customer Information
Title source: cnaDescription
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.
References (1)
Core 1
Core References
Exploit exploit
vdb-entry
technical-description
https://wpscan.com/vulnerability/501b2929-3216-4587-8124-088fd51becf1/
Scores
CVSS v3
6.1
EPSS
0.0015
EPSS Percentile
4.6%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
CISA SSVC
Vulnrichment
Exploitation
poc
Automatable
no
Technical Impact
partial
Details
CWE
CWE-79
Status
published
Products (1)
None/Simply Schedule Appointments
< 1.6.12.4
Published
Jul 27, 2026
Tracked Since
Jul 27, 2026