Appointment Booking Calendar — Simply Schedule Appointments Booking Plugin <= 1.6.12.10 - Authenticated (Contributor+) Insecure Direct Object Reference to Sensitive Information Exposure

6.5
Authorization Bypass Through User-Controlled Key
CVE CVE-2026-13358
CVSS 6.5 (Medium)
Publicly Published August 15, 2026
Last Updated August 16, 2026
Researcher Michael Iden (Mickhat) - Hack The Box

Description

The Appointment Booking Calendar — Simply Schedule Appointments Booking Plugin plugin for WordPress is vulnerable to Insecure Direct Object Reference in all versions up to, and including, 1.6.12.10 via the ssa_past_appointments due to missing validation on a user controlled key. This makes it possible for authenticated attackers, with contributor-level access and above, to access appointment records belonging to arbitrary users and harvest the per-appointment ownership tokens (32-character hashes) embedded in the rendered HTML, which can then be used without any authentication to read or modify those appointments including full customer PII such as name, email, phone number, and private notes. The /wp-json/ssa/v1/render-shortcode REST endpoint is registered unconditionally on rest_api_init regardless of whether the Divi theme is installed, and its permission callback only requires current_user_can('edit_posts'), meaning any Contributor-level account is sufficient to trigger this entire exploit chain.

References

Share

Vulnerability Details for Simply Schedule Appointments

Software Type Plugin
Software Slug simply-schedule-appointments (view on wordpress.org)
Patched? Yes
Remediation Update to version 1.6.12.11, or a newer patched version
Affected Version
  • <= 1.6.12.10
Patched Version
  • 1.6.12.11

Recent vulnerabilities in Simply Schedule Appointments

# Title CVE ID CVSS Researchers Date
1 Simply Schedule Appointments <= 1.6.12.23 - Cross-Site Request Forgery CVE-2026-84764 4.3 Anthony Green of Greenhat Security September 2, 2026
2 Simply Schedule Appointments <= 1.6.12.16 - Authenticated (Team Member+) Information Exposure CVE-2026-16541 4.3 Yaswanth Reddy Sunkara August 13, 2026
3 Simply Schedule Appointments < 1.6.12.6 - Unauthenticated Insecure Direct Object Reference CVE-2026-16540 5.3 Suleyman Huseynov August 6, 2026
4 Simply Schedule Appointments <= 1.6.12.10 - Unauthenticated SQL Injection CVE-2026-65508 7.5 daroo July 28, 2026
5 Simply Schedule Appointments <= 1.6.12.10 - Unauthenticated Stored Cross-Site Scripting CVE-2026-65513 7.2 whitebyte July 28, 2026
6 Simply Schedule Appointments <= 1.6.12.10 - Missing Authorization to Authenticated (Contributor+) Sensitive Data Disclosure CVE-2026-15254 4.3 Meher Sudhakar Abbireddi July 23, 2026
7 Appointment Booking Calendar — Simply Schedule Appointments Booking Plugin <= 1.6.12.4 - Missing Authorization CVE-2026-57812 5.3 hio July 9, 2026
8 Appointment Booking Calendar — Simply Schedule Appointments Booking Plugin <= 1.6.11.11 - Missing Authorization CVE-2026-59523 5.3 anhcd05 July 9, 2026
9 Simply Schedule Appointments <= 1.6.12.3 - Unauthenticated Stored Cross-Site Scripting CVE-2026-13400 7.2 Revanth Hari Narayana Matte July 6, 2026
10 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

Did you know Wordfence Intelligence provides free personal and commercial API access to our comprehensive WordPress vulnerability database, along with a free webhook integration to stay on top of the latest vulnerabilities added and updated in the database? Get started today!

Learn more

Want to get notified of the latest vulnerabilities that may affect your WordPress site?
Install Wordfence on your site today to get notified immediately if your site is affected by a vulnerability that has been added to our database.

Get Wordfence

The Wordfence Intelligence WordPress vulnerability database is completely free to access and query via API. Please review the documentation on how to access and consume the vulnerability data via API.

Documentation