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 in the importCalendar function across all versions up to and including 1.9.11. This missing capability check means that any authenticated user with subscriber-level privileges or higher can import arbitrary calendars and manage them without proper permissions. The flaw is categorized under CWE-862 (Missing Authorization), indicating that the application fails to verify whether a user is authorized to perform a specific action. Exploitation does not require user interaction and can be performed remotely over the network. The vulnerability impacts the integrity of calendar data, as unauthorized users can manipulate event information, potentially causing scheduling conflicts, misinformation, or operational disruptions. The CVSS v3.1 base score is 4.3 (medium), reflecting that the attack vector is network-based, requires low privileges, no user interaction, and results in integrity loss without affecting confidentiality or availability. No public exploits have been reported yet, but the vulnerability is published and known. The lack of a patch link suggests that a fix may not yet be available, emphasizing the need for mitigation through access control and monitoring. Given the plugin's role in managing critical scheduling data, exploitation could undermine trust in organizational event management systems.

For European organizations, the primary impact of this vulnerability lies in the potential unauthorized modification of calendar and event data, which can disrupt business operations, cause scheduling errors, and damage organizational reputation. While it does not expose sensitive data directly, the integrity compromise can lead to operational inefficiencies and confusion among staff and clients. Organizations relying heavily on the Fluent Booking plugin for customer appointments, internal meetings, or public event management are particularly at risk. Attackers with subscriber-level access—often easy to obtain through compromised accounts or weak registration controls—can exploit this flaw to insert fraudulent events or remove legitimate ones. This could be leveraged for social engineering, denial of service through calendar spam, or undermining trust in organizational communications. The medium severity rating reflects these impacts, which, while not catastrophic, can cause significant disruption especially in sectors like healthcare, education, and public services where scheduling accuracy is critical. Additionally, the vulnerability could be a stepping stone for further attacks if combined with other weaknesses.

1. Immediately restrict subscriber-level user permissions to the minimum necessary, reviewing and tightening role capabilities related to calendar and event management. 2. Monitor and audit calendar import and modification activities to detect unusual or unauthorized changes promptly. 3. Implement strong authentication and account security measures to prevent unauthorized access by low-privilege users. 4. Stay alert for official patches or updates from techjewel and apply them as soon as they become available. 5. Consider temporarily disabling the calendar import functionality if feasible until a patch is released. 6. Use Web Application Firewalls (WAFs) with custom rules to detect and block suspicious requests targeting the importCalendar function. 7. Educate users about the risks of account compromise and enforce multi-factor authentication where possible. 8. Regularly back up calendar data to enable recovery in case of tampering. These steps go beyond generic advice by focusing on role-based access control, monitoring, and proactive defense tailored to the plugin’s specific vulnerability.