CVE-2026-94074 in Simply Schedule Appointments Plugin
Summary
by MITRE • 09/30/2026
Unauthenticated Broken Access Control in Simply Schedule Appointments <= 1.6.12.29 versions.
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Analysis
by VulDB Data Team • 09/30/2026
The vulnerability identified as an unbroken access control issue within the Simply Schedule Appointments plugin, affecting versions up to and including 1.6.12.29, represents a critical failure in server-side authorization mechanisms. This flaw allows any user, regardless of authentication status or privilege level, to perform actions that should be restricted to administrators or authenticated users with specific roles. In the context of web application security, this type of vulnerability is fundamentally rooted in the absence of proper checks on the server side when processing requests for sensitive endpoints. The plugin fails to verify whether the requesting user has the necessary permissions before executing administrative functions, thereby bypassing intended access restrictions entirely. This aligns directly with CWE-284, which describes Improper Access Control, and is further categorized under ATT&CK technique T1078, Valid Accounts, as it allows attackers to leverage default or unauthenticated states to gain unauthorized influence over the application's configuration and data.
The technical mechanism behind this flaw typically involves insecure direct object references or missing function-level access controls within the plugin’s AJAX handlers or REST API endpoints. When a request is made to modify appointment settings, manage users, or alter database records associated with scheduling configurations, the server processes these requests without validating the session token or user role against an allowlist of permitted actions for that specific endpoint. This oversight means that malicious actors can craft HTTP POST or GET requests containing arbitrary parameters to execute administrative commands remotely. The lack of validation extends beyond simple page access; it encompasses state-changing operations such as creating new admin users, deleting existing appointments, or modifying plugin settings without any form of cross-site request forgery protection or nonce verification being effectively enforced for all critical paths.
The operational impact of this vulnerability is severe due to the high-privilege nature of the affected functions in a scheduling application. An attacker can achieve full compromise of the WordPress installation by exploiting these endpoints to escalate privileges, potentially creating new administrator accounts that provide persistent backdoor access. Furthermore, because appointment data often contains personally identifiable information such as names, contact details, and scheduled times, unauthorized modification or deletion of this data constitutes a significant breach of confidentiality and integrity. This can lead to direct financial loss for businesses relying on the plugin for service bookings, reputational damage due to disrupted services, and potential regulatory penalties under frameworks like GDPR if customer data is exposed or altered without consent. The ability to manipulate scheduling logic also allows attackers to disrupt business operations by clearing calendars or inserting malicious appointments that could be used for phishing campaigns targeting clients who receive automated confirmations from the compromised system.
Mitigation strategies must prioritize immediate remediation through software updates and defensive configuration changes. Users running versions of Simply Schedule Appointments prior to 1.6.12.30 should upgrade to the latest patched version immediately, as this release addresses the authorization checks for administrative endpoints. In environments where upgrading is not instantly feasible, temporary mitigations include restricting access to WordPress admin-ajax.php and REST API routes via web application firewall rules that require valid authentication tokens or restrict IP ranges to trusted sources only. Additionally, implementing strict Content Security Policy headers can help mitigate some aspects of cross-site scripting vectors often associated with such flaws, although they do not directly fix the underlying authorization failure. Regular security audits focusing on function-level access control verification are essential to ensure that no other endpoints in the plugin or theme remain vulnerable to similar unauthenticated exploitation patterns.