CVE-2026-59523 in Simply Schedule Appointments Plugin
Summary
by MITRE • 07/13/2026
Missing Authorization vulnerability in NSquared Simply Schedule Appointments simply-schedule-appointments allows Exploiting Incorrectly Configured Access Control Security Levels.This issue affects Simply Schedule Appointments: from n/a through <= 1.6.11.11.
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Analysis
by VulDB Data Team • 07/13/2026
This vulnerability represents a critical missing authorization flaw that undermines the access control mechanisms within the NSquared Simply Schedule Appointments plugin. The security weakness stems from incorrectly configured access control security levels that fail to properly validate user permissions before granting access to sensitive functionality. This misconfiguration allows unauthorized users to bypass normal authentication checks and access appointment management features that should only be available to authenticated administrators or authorized personnel. The vulnerability exists across all versions from the initial release through version 1.6.11.11, indicating a persistent flaw in the plugin's permission handling architecture.
The technical implementation of this vulnerability manifests as insufficient input validation and privilege escalation opportunities within the plugin's core access control system. Attackers can exploit this weakness by crafting specific requests that circumvent the normal authorization flow, potentially gaining access to appointment data, scheduling capabilities, and administrative functions without proper authentication credentials. This flaw directly maps to CWE-285, which addresses improper authorization issues in software systems, and aligns with ATT&CK technique T1078 for valid accounts and privilege escalation. The vulnerability's impact extends beyond simple information disclosure as it enables full manipulation of the scheduling system.
The operational consequences of this missing authorization vulnerability are severe for organizations relying on the Simply Schedule Appointments plugin for their business operations. Unauthorized access to appointment booking systems could lead to data breaches, service disruption, financial loss through fraudulent bookings, and potential compliance violations. Attackers might exploit this weakness to view confidential client information, modify existing appointments, create unauthorized bookings, or even delete critical scheduling data. The vulnerability affects not only the immediate plugin functionality but also poses risks to broader organizational security posture, particularly in environments where multiple users interact with shared appointment systems.
Mitigation strategies should focus on implementing proper access control validation throughout the plugin's codebase, ensuring that all sensitive operations require explicit authentication and authorization checks before execution. Organizations should immediately update to the latest version of the plugin where this vulnerability has been addressed through proper access control implementation. Security measures including input sanitization, role-based access controls, and comprehensive logging of access attempts should be implemented to detect potential exploitation attempts. Additionally, regular security audits and penetration testing of web applications should include thorough examination of access control mechanisms to identify similar misconfigurations that could lead to privilege escalation vulnerabilities.