The vulnerability identified as CVE-2025-12787 affects the Hydra Booking — Appointment Scheduling & Booking Calendar plugin for WordPress, versions up to and including 1.1.27. The root cause is the use of insufficiently random values in generating booking cancellation tokens within the plugin's tfhb_meeting_form_submit_callback function. Additionally, the plugin uses a globally shared nonce, which further weakens the security of the cancellation mechanism. This combination allows unauthenticated attackers to perform brute force attacks against the tfhb_meeting_form_cencel AJAX endpoint to guess valid cancellation tokens. Successful exploitation enables attackers to cancel arbitrary bookings without any authentication or user interaction, compromising the integrity of booking data. The vulnerability is classified under CWE-330, which concerns the use of insufficiently random values that can be predicted or brute-forced. The CVSS v3.1 base score is 5.3 (medium), reflecting the network attack vector, low attack complexity, no privileges required, and no user interaction needed. There is no impact on confidentiality or availability, but integrity is affected due to unauthorized booking cancellations. No patches or known exploits are currently available, and the vulnerability was published on November 11, 2025.

For European organizations, especially those relying on the Hydra Booking plugin for managing appointments and bookings, this vulnerability poses a risk of unauthorized booking cancellations. This can lead to operational disruptions, customer dissatisfaction, and potential reputational damage. Attackers could exploit this flaw to disrupt business workflows, cause confusion among clients, or manipulate booking records. While the vulnerability does not expose sensitive data or cause denial of service, the integrity compromise could affect service reliability and trustworthiness. Organizations in sectors such as healthcare, education, hospitality, and professional services that use this plugin for client scheduling are particularly vulnerable. The ease of exploitation without authentication increases the risk of automated attacks targeting multiple organizations. Although no known exploits are reported in the wild, the public disclosure may prompt attackers to develop exploit tools, increasing the threat over time.

Since no official patch is currently available, European organizations should implement immediate compensating controls. These include restricting access to the tfhb_meeting_form_cencel AJAX endpoint via web application firewalls (WAFs) or IP whitelisting to limit exposure to trusted networks. Monitoring web server logs for unusual or repeated cancellation requests can help detect brute force attempts early. Organizations should consider temporarily disabling the booking cancellation feature if feasible until a secure update is released. Updating the plugin promptly once a patch is available is critical. Additionally, implementing multi-factor authentication or CAPTCHA mechanisms around booking management interfaces can reduce automated abuse. Educating staff and users about potential booking anomalies and encouraging verification of cancellations can mitigate impact. Regular backups of booking data will aid recovery if unauthorized cancellations occur. Finally, maintaining an updated inventory of WordPress plugins and their vulnerabilities supports proactive risk management.