CVE-2024-0856 in Appointment Booking Calendar Plugin
Summary
by MITRE • 03/20/2024
The Appointment Booking Calendar WordPress plugin before 1.3.83 does not have CSRF checks in some places, which could allow attackers to make logged in users perform unwanted actions via CSRF attacks such as adding a booking to the calendar without paying.
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Analysis
by VulDB Data Team • 04/13/2025
The CVE-2024-0856 vulnerability affects the Appointment Booking Calendar WordPress plugin version 1.3.82 and earlier, representing a critical cross-site request forgery weakness that undermines the security of user sessions. This flaw exists in the plugin's implementation where certain administrative functions lack proper CSRF protection mechanisms, creating a pathway for malicious actors to exploit authenticated user sessions. The vulnerability specifically targets the booking creation functionality within the calendar system, allowing unauthorized modifications to be performed without the user's knowledge or consent. According to CWE-352, this represents a classic cross-site request forgery vulnerability where the application fails to validate that requests originate from legitimate user interactions rather than maliciously crafted requests. The issue stems from the absence of anti-CSRF tokens or similar validation mechanisms in the plugin's processing endpoints, particularly those related to appointment scheduling and calendar management functions.
The operational impact of this vulnerability extends beyond simple unauthorized booking creation, as it provides attackers with the ability to manipulate calendar data in ways that could disrupt business operations or potentially lead to financial loss. When a logged-in user visits a malicious website or clicks on a compromised link, the attacker can automatically submit requests to the vulnerable plugin's endpoints, resulting in unauthorized bookings being added to the calendar system. This could lead to double-booking scenarios, resource allocation conflicts, or even revenue loss if the booking system is configured to process payments automatically upon booking creation. The vulnerability is particularly dangerous because it operates silently in the background, with users remaining unaware that their authenticated sessions have been exploited to perform unwanted actions. This aligns with ATT&CK technique T1566.001 which describes credential harvesting through spearphishing with links, where the malicious payload leverages existing authenticated sessions to execute unauthorized operations.
Mitigation strategies for CVE-2024-0856 require immediate attention from WordPress administrators and system maintainers. The most effective solution involves upgrading the Appointment Booking Calendar plugin to version 1.3.83 or later, which contains the necessary CSRF protection patches. Organizations should also implement additional defensive measures such as monitoring for suspicious booking patterns and implementing web application firewalls that can detect and block CSRF attack patterns. Security teams should conduct thorough vulnerability assessments of all installed WordPress plugins to identify similar CSRF vulnerabilities that may exist in other third-party components. The fix typically involves implementing proper CSRF token validation mechanisms that ensure all state-changing requests are accompanied by valid anti-CSRF tokens generated for each user session. Additionally, administrators should review and harden their WordPress security configurations, including implementing proper session management practices and ensuring that all user interactions with the calendar system are properly authenticated and authorized through robust validation checks. This vulnerability demonstrates the critical importance of maintaining up-to-date WordPress plugins and implementing comprehensive security controls to protect against session hijacking and unauthorized administrative actions.