CVE-2025-13756 is a vulnerability identified in the Fluent Booking plugin for WordPress, a widely used solution for appointment scheduling, event booking, and calendar management. The issue arises from a missing authorization check (CWE-862) in the plugin's importCalendar function across all versions up to and including 1.9.11. This flaw allows any authenticated user with subscriber-level privileges or higher to import arbitrary calendars and manage them without proper permission validation. The vulnerability is remotely exploitable without user interaction and requires only low complexity, as the attacker must be authenticated but no further privileges are necessary. The impact is limited to integrity, as unauthorized users can manipulate calendar data, potentially causing misinformation or disruption in event scheduling. Confidentiality and availability are not directly affected. No patches are currently linked, and no known exploits have been reported in the wild as of the publication date. The vulnerability affects all installations of the plugin up to version 1.9.11, which is used globally on WordPress sites that rely on event and appointment management features. The CVSS v3.1 score is 4.3, reflecting a medium severity level due to the limited scope and impact but ease of exploitation by low-privileged users.

The primary impact of CVE-2025-13756 is on the integrity of calendar data within affected WordPress sites using the Fluent Booking plugin. Unauthorized users with subscriber-level access can import and manage calendars, potentially leading to misinformation, scheduling conflicts, or unauthorized events being added or modified. This can disrupt business operations, cause reputational damage, and reduce trust in the affected organization's event management processes. While confidentiality and availability are not directly compromised, the manipulation of calendar data can indirectly affect organizational workflows and customer experience. Organizations relying heavily on accurate scheduling for client appointments, events, or resource management are particularly at risk. The vulnerability could also be leveraged as a foothold for further attacks if combined with other vulnerabilities or social engineering tactics. Given the widespread use of WordPress and event management plugins, the scope of affected systems is significant, especially for small to medium businesses that may not have stringent access controls or monitoring in place.

To mitigate CVE-2025-13756, organizations should first monitor for updates or patches released by the plugin vendor and apply them promptly once available. In the absence of an official patch, administrators should restrict user roles to the minimum necessary privileges, ensuring that only trusted users have subscriber-level or higher access. Implementing strict role-based access controls can limit the number of users capable of exploiting this vulnerability. Additionally, monitoring and logging calendar import activities can help detect unauthorized changes early. If possible, temporarily disabling the calendar import functionality or the entire plugin until a fix is applied can prevent exploitation. Organizations should also educate users about the risks of granting unnecessary permissions and review user accounts regularly to remove or downgrade unnecessary privileges. Employing a web application firewall (WAF) with custom rules to detect and block suspicious calendar import requests may provide an additional layer of defense. Finally, maintaining regular backups of calendar data ensures recovery in case of unauthorized modifications.