The vulnerability identified as CVE-2025-13756 affects the Fluent Booking plugin for WordPress, a widely used solution for appointment scheduling, event booking, and calendar management. The core issue is a missing authorization check (CWE-862) in the importCalendar function across all versions up to and including 1.9.11. This flaw allows any authenticated user with subscriber-level permissions or higher to import arbitrary calendars and manage them without proper capability verification. Since subscriber-level access is relatively low privilege, this significantly broadens the attack surface within affected WordPress sites. The vulnerability does not require user interaction beyond authentication, and the attack vector is network-based, making remote exploitation feasible. The CVSS 3.1 base score is 4.3 (medium), reflecting that while confidentiality and availability are not impacted, integrity can be compromised due to unauthorized calendar modifications. No patches were linked at the time of disclosure, and no known exploits have been reported in the wild. The vulnerability could be leveraged to manipulate event data, inject misleading information, or disrupt scheduling workflows, potentially affecting business operations relying on accurate calendar data. The flaw stems from inadequate capability checks, a common authorization weakness, underscoring the importance of strict role-based access controls in WordPress plugins handling sensitive operational data.

For European organizations, especially those relying on WordPress-based event and appointment management, this vulnerability poses a risk to data integrity and operational reliability. Unauthorized calendar imports and management could lead to misinformation, scheduling conflicts, or unauthorized event creation, which may disrupt business processes, customer interactions, and internal coordination. While the vulnerability does not expose sensitive data directly or cause denial of service, the integrity compromise can erode trust in the affected systems and potentially cause reputational damage. Organizations in sectors such as healthcare, education, professional services, and event management that use Fluent Booking could face operational disruptions. Additionally, attackers could use this foothold to further escalate privileges or conduct social engineering attacks by manipulating event information. The medium severity indicates that while the threat is not critical, it requires timely attention to prevent exploitation and downstream impacts.

1. Monitor for and apply official patches or updates from the plugin vendor as soon as they become available to address the missing authorization check. 2. Until patches are released, restrict user roles and permissions rigorously, limiting subscriber-level access to trusted users only. 3. Implement additional access controls at the WordPress level, such as custom capability checks or security plugins that can enforce stricter authorization on calendar import functions. 4. Audit and monitor calendar-related activities and logs to detect unauthorized imports or modifications promptly. 5. Consider temporarily disabling the importCalendar functionality if feasible, or replacing the plugin with alternative solutions that enforce proper authorization. 6. Educate administrators and users about the risks of unauthorized calendar changes and encourage vigilance for suspicious events or scheduling anomalies. 7. Employ web application firewalls (WAFs) with rules targeting abnormal calendar import requests to mitigate exploitation attempts. 8. Regularly review user roles and remove unnecessary accounts to reduce the attack surface.