CVE-2026-11821 in Eventin Plugin
Summary
by MITRE • 09/09/2026
The Eventin – Event Calendar, Event Registration, Tickets & Booking (AI Powered) plugin for WordPress is vulnerable to authorization bypass in all versions up to, and including, 4.1.17. This is due to the plugin not properly verifying that a user is authorized to perform an action. This makes it possible for authenticated attackers, with subscriber-level access and above, to view, create, update, clone, and delete notification flow event automation workflows that should be restricted to administrators.
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Analysis
by VulDB Data Team • 09/09/2026
The vulnerability identified in the Eventin – Event Calendar, Event Registration, Tickets & Booking plugin for WordPress represents a critical authorization bypass flaw affecting all versions up through 4.1.17. This security defect stems from an insufficient verification of user privileges when handling specific administrative actions within the plugin's notification flow event automation system. In secure software architecture, functions that modify or manage sensitive configuration data must enforce strict role-based access control to ensure that only users with elevated permissions can execute these operations. The absence of such checks in this plugin allows any authenticated user possessing subscriber-level access and above to interact with administrative features intended exclusively for site administrators. This misconfiguration fundamentally undermines the principle of least privilege, which dictates that users should be granted only the minimum levels of access necessary to perform their job functions.
From a technical perspective, the flaw resides in the API endpoints or internal handlers responsible for managing notification flow event automation workflows. These components fail to validate whether the requesting user possesses the administrator role before processing requests related to viewing, creating, updating, cloning, and deleting these automated sequences. Consequently, an attacker with even basic authenticated access can manipulate the plugin's core functionality without triggering any authorization errors or requiring additional authentication steps. This lack of server-side validation allows for direct manipulation of state-changing operations that should be restricted by design. The vulnerability is particularly dangerous because it does not require complex exploitation techniques; rather, it relies on the straightforward misuse of existing interfaces due to inadequate permission checks during request processing.
The operational impact of this authorization bypass is significant and multifaceted. Attackers can disrupt event management workflows by deleting critical notification sequences, which may prevent attendees from receiving essential updates regarding events they have registered for or tickets they have purchased. Furthermore, the ability to create or update these workflows allows an attacker to inject malicious logic into the automation process, potentially leading to data exfiltration via unauthorized email notifications or spamming of user bases with forged messages. The capability to clone existing configurations could also be used to replicate sensitive settings across different contexts for further exploitation. These actions compromise the integrity and availability of the event management system, eroding trust among users and potentially causing financial losses through disrupted ticket sales or reputational damage due to poor communication failures during live events.
This vulnerability aligns with CWE-284, which describes Improper Access Control, specifically highlighting cases where access control is not properly enforced for specific actions. Additionally, it maps to the MITRE ATT&CK framework under techniques related to Privilege Escalation and Defense Evasion, as attackers leverage existing authenticated sessions to perform administrative tasks without detection or proper authorization checks. The exploitation of this flaw falls within the broader category of Broken Access Control, which remains one of the most prevalent risks in web applications according to OWASP guidelines. By bypassing intended restrictions, an attacker effectively elevates their privileges from a low-level subscriber to that of an administrator regarding specific plugin functionalities, thereby gaining control over critical business logic components.
To mitigate this risk, immediate action is required by upgrading the Eventin plugin to version 4.1.18 or later, where these authorization checks have been properly implemented and validated. Administrators should also audit user roles within their WordPress installation to ensure that only trusted individuals hold subscriber-level access if they do not require any interaction with the event management system. Implementing a Web Application Firewall can provide an additional layer of defense by monitoring for anomalous patterns in API requests, although this is not a substitute for fixing the underlying code defect. Regular security audits and penetration testing should be conducted to identify similar authorization flaws across other plugins installed on the server, ensuring that role-based access controls are consistently enforced throughout the entire application stack.