Appointment Booking Calendar <= 1.6.11.8 - Missing Authorization to Unauthenticated Arbitrary Modification via Bulk Appointments REST API Endpoint

5.3
Missing Authorization
CVE CVE-2026-6937
CVSS 5.3 (Medium)
Publicly Published May 27, 2026
Last Updated May 28, 2026
Researcher winrace

Description

The Appointment Booking Calendar — Simply Schedule Appointments Booking Plugin plugin for WordPress is vulnerable to Missing Authorization in all versions up to, and including, 1.6.11.8 due to the plugin not properly verifying that a user is authorized to perform an action via the bulk appointments REST API endpoint. This makes it possible for unauthenticated attackers to modify arbitrary appointment records including customer PII, payment status, and meeting URL fields, and to expose full customer PII from existing appointment records via the bulk endpoint response. The public nonce is a static, user-independent value present in the HTML source of any page hosting the [ssa_booking] shortcode, meaning any visitor who has viewed such a page can obtain it and target any appointment in the system without authentication.

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Vulnerability Details for Simply Schedule Appointments

Software Type Plugin
Software Slug simply-schedule-appointments (view on wordpress.org)
Patched? Yes
Remediation Update to version 1.6.11.9, or a newer patched version
Affected Version
  • <= 1.6.11.8
Patched Version
  • 1.6.11.9

Recent vulnerabilities in Simply Schedule Appointments

# Title CVE ID CVSS Researchers Date
1 Simply Schedule Appointments < 1.6.12.6 - Unauthenticated Insecure Direct Object Reference CVE-2026-16540 5.3 Suleyman Huseynov August 6, 2026
2 Simply Schedule Appointments <= 1.6.12.10 - Unauthenticated SQL Injection CVE-2026-65508 7.5 daroo July 28, 2026
3 Simply Schedule Appointments <= 1.6.12.10 - Unauthenticated Stored Cross-Site Scripting CVE-2026-65513 7.2 whitebyte July 28, 2026
4 Appointment Booking Calendar — Simply Schedule Appointments Booking Plugin <= 1.6.11.11 - Missing Authorization CVE-2026-59523 5.3 anhcd05 July 9, 2026
5 Appointment Booking Calendar — Simply Schedule Appointments Booking Plugin <= 1.6.12.4 - Missing Authorization CVE-2026-57812 5.3 hio July 9, 2026
6 Simply Schedule Appointments <= 1.6.12.3 - Unauthenticated Stored Cross-Site Scripting CVE-2026-13400 7.2 Revanth Hari Narayana Matte July 6, 2026
7 Appointment Booking Calendar — Simply Schedule Appointments Booking Plugin <= 1.6.12.2 - Unauthenticated Stored Cross-Site Scripting CVE-2026-57317 7.2 vnth4nhnt June 26, 2026
8 Appointment Booking Calendar — Simply Schedule Appointments Booking Plugin <= 1.6.10.6 - Unauthenticated Stored Cross-Site Scripting CVE-2026-39447 7.2 devploit May 28, 2026
9 Appointment Booking Calendar <= 1.6.11.8 - Unauthenticated SQL Injection via 'append_where_sql' Parameter CVE-2026-7797 7.5 daroo May 27, 2026
10 Appointment Booking Calendar — Simply Schedule Appointments Booking Plugin <= 1.6.11.5 - Unauthenticated Denial of Service CVE-2026-7493 5.3 lucky_buddy May 26, 2026

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