CVE-2026-6937 | Appointment Booking Calendar <= 1.6.11.8 - Missing Authorization to Unauthenticated Arbitrary Modification via Bulk Appointments REST API Endpoint

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.

Published: 2026-05-28 Last update: 2026-05-28 Assigner: [email protected] Source: [email protected]

Conclusion & alert: CVE-2026-6937 is rated Low Risk (31.6/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.38%). Mandatory action: Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-6937

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.18% 0.38% +0.20%
2 2026-05-28 0.18%

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-6937

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
3.9 1.4 [email protected]

Weakness enumeration for CVE-2026-6937

GitHub Security Advisory for CVE-2026-6937

GHSA-4cp9-7xpg-wmvc · Severity: medium — The Appointment Booking Calendar — Simply Schedule Appointments Booking Plugin plugin for...

Affected software / configurations for CVE-2026-6937

Vendor Product Version Raw CPE
No affected products in dataset.

References for CVE-2026-6937

URL Tags
https://plugins.trac.wordpress.org/browser/simply-schedule-appointments/tags/1.6.10.0/includes/class-appointment-model.php#L724
https://plugins.trac.wordpress.org/browser/simply-schedule-appointments/tags/1.6.10.0/includes/class-bootstrap.php#L151
https://plugins.trac.wordpress.org/browser/simply-schedule-appointments/tags/1.6.10.0/includes/lib/td-util/class-td-api-model.php#L74
https://plugins.trac.wordpress.org/browser/simply-schedule-appointments/tags/1.6.11.0/includes/class-appointment-model.php#L724
https://plugins.trac.wordpress.org/browser/simply-schedule-appointments/tags/1.6.11.0/includes/class-bootstrap.php#L151
https://plugins.trac.wordpress.org/browser/simply-schedule-appointments/tags/1.6.11.0/includes/lib/td-util/class-td-api-model.php#L74
https://plugins.trac.wordpress.org/browser/simply-schedule-appointments/trunk/includes/class-appointment-model.php#L724
https://plugins.trac.wordpress.org/browser/simply-schedule-appointments/trunk/includes/class-bootstrap.php#L151
https://plugins.trac.wordpress.org/browser/simply-schedule-appointments/trunk/includes/lib/td-util/class-td-api-model.php#L74
https://plugins.trac.wordpress.org/changeset?sfp_email=&sfph_mail=&reponame=&old=3549843%40simply-schedule-appointments&new=3549843%40simply-schedule-appointments&sfp_email=&sfph_mail=
https://www.wordfence.com/threat-intel/vulnerabilities/id/ef0f5f9d-788a-4cf8-9747-ada076a69a1f?source=cve
cvelogic Threat Intelligence