CVE-2025-13756 in Fluent Booking Plugin
Summary
by MITRE • 12/03/2025
The Fluent Booking plugin for WordPress is vulnerable to unauthorized calendar import and management due to a missing capability check on the "importCalendar" function in all versions up to, and including, 1.9.11. This makes it possible for authenticated attackers, with subscriber level access and above, to import arbitrary calendars and manage them.
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Analysis
by VulDB Data Team • 12/03/2025
The vulnerability identified as CVE-2025-13756 affects the Fluent Booking plugin for WordPress, a popular calendar management solution that enables users to create and manage booking systems. This security flaw stems from a critical missing capability check within the plugin's codebase, specifically targeting the "importCalendar" function that exists across all versions up to and including 1.9.11. The absence of proper authorization controls creates a significant privilege escalation vector that allows attackers with minimal user permissions to exploit this weakness. The vulnerability impacts the core functionality of calendar management within the WordPress environment, potentially enabling malicious actors to manipulate scheduling data and disrupt normal operations.
The technical implementation of this vulnerability resides in the lack of capability verification within the importCalendar function, which should require administrative privileges to perform calendar import operations. According to CWE-285, this represents an insufficient authorization flaw where the system fails to properly verify that the requesting user has the necessary permissions to execute the operation. The flaw operates at the application level where the plugin does not validate user roles or capabilities before allowing calendar import functionality. This missing validation allows authenticated users at the subscriber level and above to bypass normal access controls that should restrict calendar management operations to administrators or designated users with appropriate privileges.
From an operational perspective, this vulnerability creates serious implications for WordPress sites using the Fluent Booking plugin, as it enables unauthorized calendar manipulation that can lead to various security and operational issues. Attackers with subscriber-level access can import arbitrary calendar data, potentially including malicious entries that could disrupt scheduling, create false availability information, or even serve as a vector for further attacks. The impact extends beyond simple calendar management as calendar data often contains sensitive scheduling information, appointment details, and user booking records that could be exploited for social engineering or data manipulation attacks. This vulnerability aligns with ATT&CK technique T1078 which covers legitimate credentials use for persistence and privilege escalation, as attackers can leverage existing user accounts to perform unauthorized administrative functions.
Organizations using the Fluent Booking plugin should immediately implement mitigations to address this vulnerability. The primary recommendation involves upgrading to the latest version of the plugin where the capability check has been properly implemented and validated. System administrators should also consider implementing additional monitoring and access control measures to detect unauthorized calendar import activities. The vulnerability demonstrates the critical importance of proper input validation and capability checks in web applications, particularly in plugins that handle user data and scheduling information. Security teams should review all plugin installations for similar authorization flaws and ensure that proper role-based access controls are enforced throughout the WordPress ecosystem. Regular security audits and vulnerability assessments should include checks for missing capability validations in custom and third-party plugins to prevent similar issues from compromising system integrity.