Payment Validation Flaw in Appointment Booking Calendar Plugin by WordPress
CVE-2026-76586

7.5HIGH

Key Information:

Vendor

WordPress
Status
Appointment Booking Calendar Plugin And Scheduling Plugin
Vendor
CVE Published:
29 August 2026

Badges

👾 Exploit Exists🟡 Public PoC

What is CVE-2026-76586?

The Appointment Booking Calendar and Scheduling plugins for WordPress prior to version 1.6.3 exhibit a serious issue where the actual payment amount is not verified against the expected server-side price during the online payment confirmation process. This flaw enables unauthenticated users to secure appointments at a significantly reduced price, compromising the integrity of appointment bookings and potential revenue.

Affected Version(s)

Appointment Booking Calendar Plugin and Scheduling Plugin 1.5.6 < 1.6.3

Exploit Proof of Concept (PoC)

PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.

CVE-2026-76586 - Proof of Concept

References

https://wpscan.com/vulnerability/bc74bc9b-92ce-434e-a21d-...
exploitvdb-entrytechnical-description

CVSS V3.1

Score:
7.5
Severity:
HIGH
Confidentiality:
None
Integrity:
High
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

Credit

Nguyen Phuoc Thinh - HPT Vietnam Corporation
WPScan
.