CVE-2026-13358: Appointment Booking Calendar — Simply Schedule Appointments Booking: Insecure Direct Object Reference

Appointment Booking Calendar — Simply Schedule Appointments Booking: Insecure Direct Object Reference

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.

Description from the National Vulnerability Database, published by Wordfence

What it means for a small business

Appointment Booking Calendar — Simply Schedule Appointments Booking is a WordPress plugin. If your website uses it, the flaw is on your site whether or not anyone has noticed yet: attackers scan the whole internet for the plugins with published flaws, usually within days of a record like this one going public.

Most small-business sites run 15 to 40 plugins, and few owners know the list. You can check from WordPress itself (Plugins, then Installed Plugins), or let our free plugin check look it up by name.

Check your own setup

Is Appointment Booking Calendar — Simply Schedule Appointments Booking on the danger list? Our free plugin check shows every recorded flaw for it and the version that fixes each.
Website check: reads what your site runs from the outside (WordPress version, plugins it can see, old server software) and matches it against this database.
Server check: what your web server says about itself, and whether that version has known flaws.

Sources

Part of the Huttenlocher Technologies vulnerability database, refreshed twice a day from CISA and the NVD. The title, category and plain-language guidance are ours; check the linked record before acting on a detail. This is general guidance, not a review of your systems.

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