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Simply Schedule Appointments < 1.6.12.6 — Unauthenticated Insecure Direct Object Reference

CVE-2026-16540Published · Updated

Action summary

Affected: <1.6.12.6Update to 1.6.12.6 or newer

All remediation steps
Watch plugin
Severity
Medium5.3
CVSS
5.3
CVSS 3.1 · CNA (Wordfence)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
What does this vector mean?
AV:N Attack vector
Network
AC:L Attack complexity
Low
PR:N Privileges required
None
UI:N User interaction
None
S:U Scope
Unchanged
C:N Confidentiality
None
I:L Integrity
Low
A:N Availability
None
Weakness
CWE-639 Authorization Bypass Through User-Controlled Key
Required access
No account needed
Exploit prediction (EPSS)
No score
CISA KEV
Not listed
On this page8

Am I affected?

Simply Schedule Appointments simply-schedule-appointments

  1. Affected< 1.6.12.6
  2. Patched in1.6.12.6

Update to 1.6.12.6 or newer.

You are affected if you run < 1.6.12.6. Version 1.6.12.6 and later are not affected by this issue.

  • Check your version: in wp-admin go to Plugins → Installed Plugins and read the version under Simply Schedule Appointments.
  • No admin access? Run a passive check of your site. It reads public files only.
  • No account is needed to exploit this. Treat any exposed site on an affected version as at risk.

What to do

  1. Update to version 1.6.12.6, or a newer patched version
  2. Rotate administrator passwords and application secrets if the site ran a vulnerable version while publicly reachable.
  3. Watch Simply Schedule Appointments to get an email when the next vulnerability is published.

Advisory

Source description from Wordfence Intelligence, credited to Suleyman Huseynov.

The Simply Schedule Appointments plugin for WordPress is vulnerable to Insecure Direct Object Reference in versions up to 1.6.12.6 due to missing validation on a user controlled key. This makes it possible for unauthenticated attackers to perform an unauthorized action.

Exploits & references

Proof-of-concept & detection

No public proof-of-concept or detection template is known for this vulnerability.

Advisories & patches

More in Simply Schedule Appointments

All 52
More vulnerabilities in Simply Schedule Appointments
SeverityVulnerabilityCVEPublished
Medium5.3Missing Authorization
≤1.6.13.0Update to 1.6.13.4
CVE-2026-125437
High7.2Unauthenticated Stored Cross-Site Scripting
≤1.6.12.35Update to 1.6.12.37
CVE-2026-110382
Medium4.3Authenticated (Contributor+) Insecure Direct Object Reference
≤1.6.12.35Update to 1.6.12.37
CVE-2026-110381
High7.2Unauthenticated Stored Cross-Site Scripting via 'status' Parameter via /wp-json/ssa/v1/appointments/{id}
≤1.6.12.35Update to 1.6.12.37
CVE-2026-104000
Medium5.3Incorrect Authorization to Unauthenticated Sensitive Field Modification via Appointment Public Token
≤1.6.11.11Update to 1.6.12.0
CVE-2026-6723

Timeline

  1. CVE published

    Severity medium, CVSS 5.3

  2. Record last updated

Sources & licenses

Wordfence record
Vulnerability data
Wordfence Intelligence. [object Object] Licensed under the CC BY-SA 4.0.
CVE® identifiers
[object Object]. Used under the CVE Program. CVE® is a registered trademark of The MITRE Corporation.
CVSS / CWE
National Vulnerability Database (NVD), shown unmodified. This product uses the NVD API but is not endorsed or certified by the NVD.
VulnCrest content
Summary, remediation guidance and page layout © VulnCrest. Not sourced from NVD.

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