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.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "6.5",
  "pubDate": "2026-08-16T05:16:46.213Z",
  "pubdate": "2026-08-16T05:16:46.213Z",
  "executiveSummary": "An Insecure Direct Object Reference (IDOR) vulnerability exists in the Appointment Booking Calendar — Simply Schedule Appointments Booking Plugin plugin for WordPress in all versions up to, and including, 1.6.12.10 via the ssa_past_appointments key.\nThe vulnerability allows authenticated attackers with contributor-level access and above to access arbitrary user appointment records, harvest per-appointment ownership tokens (32-character hashes), and subsequently read or modify appointments without authentication.\nThe impact includes the exposure of full customer Personally Identifiable Information (PII) such as names, email addresses, phone numbers, and private notes.\nThe attack requires contributor-level privileges on the WordPress site and targets the unconditionally registered REST endpoint.\nThe risk implications are severe due to potential data leakage and unauthorized manipulation of scheduling records.",
  "technicalDetails": "The root cause of the vulnerability is missing validation on a user-controlled key within the ssa_past_appointments parameter, leading to an Insecure Direct Object Reference (IDOR).\nThe vulnerable component is associated with the /wp-json/ssa/v1/render-shortcode REST endpoint, which is registered unconditionally on rest_api_init regardless of whether the Divi theme is installed.\nThe permission callback for the endpoint only requires current_user_can('edit_posts'), meaning any Contributor-level account possesses sufficient privileges to trigger the exploit chain.\nAffected versions include all versions of the Appointment Booking Calendar — Simply Schedule Appointments Booking Plugin plugin for WordPress up to, and including, 1.6.12.10.\nThe attack flow proceeds as follows: First, an authenticated attacker with contributor-level access leverages the /wp-json/ssa/v1/render-shortcode REST endpoint. Second, by manipulating the user-controlled key via ssa_past_appointments, the attacker bypasses access controls due to missing validation. Third, the endpoint renders HTML containing appointment records belonging to arbitrary users. Fourth, the attacker harvests the embedded per-appointment ownership tokens, which consist of 32-character hashes. Finally, these harvested tokens are utilized without any authentication to read or modify those specific appointments.\nPost-exploitation impact allows unauthorized actors to harvest full customer PII, including names, email addresses, phone numbers, and private notes, as well as modify appointment data."
}