Reported vulnerability

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

Q: Which versions of Simply Schedule Appointments are affected?

Wordfence lists these affected versions: Start version unspecified, through 1.6.11.8. Use the version checker above to compare your installed release with this report.

Q: Is a fix available for Simply Schedule Appointments?

Wordfence reports a fix for this issue in Simply Schedule Appointments. It lists these fixed versions: 1.6.11.9. Back up your website and test the recommended update before applying it to your live site.

Q: Where can I find my installed plugin version?

In WordPress, open Plugins > Installed Plugins and find the version shown beneath the plugin name.

Published 27 May 2026

Updated 28 May 2026

CVE-2026-6937

Compare your installed software with the affected versions below. Follow the source’s remediation guidance and test an available update after taking a backup. A database entry describes a reported issue; it does not establish whether a particular website has been compromised.

Does this affect my version?

Check your installed version against this advisory. This compares the report’s version ranges and does not scan your website.

Wordfence advisory

medium · CVSS 5.3

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.

Severity vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Simply Schedule Appointments

Software: plugin · simply-schedule-appointments
Affected versions: Start version unspecified, through 1.6.11.8
Fix availability: Fix available
Fixed versions: 1.6.11.9

Recommended action

Update to version 1.6.11.9, or a newer patched version

Further references (1)

wordfence.com/threat-intel/vulnerabilities/id/ef0f5f9d-788a-4cf8-9747-ada076a69a1f?source=api-prod

Data sources and licences

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CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE®). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy.

Read licence terms

Source: Wordfence

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Questions about this vulnerability

Which versions of Simply Schedule Appointments are affected?

Wordfence lists these affected versions: Start version unspecified, through 1.6.11.8. Use the version checker above to compare your installed release with this report.

Is a fix available for Simply Schedule Appointments?

Wordfence reports a fix for this issue in Simply Schedule Appointments. It lists these fixed versions: 1.6.11.9. Back up your website and test the recommended update before applying it to your live site.

Where can I find my installed plugin version?

In WordPress, open Plugins > Installed Plugins and find the version shown beneath the plugin name.

Does an affected version mean my website has been hacked?

An affected version means the installed release matches a vulnerability described in this report. It does not show whether anyone has exploited it on your website. The checker compares version numbers with stored reports; it does not inspect your website.

These reports cover at least one of the same plugins, themes or WordPress core. Check each report’s affected versions separately.

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