CVE-2026-105197 in Appointment Booking Plugin
Summary
by MITRE • 10/08/2026
The Appointment Booking Plugin WordPress plugin before 5.6.5 does not verify that a backend staff user is authorized to act on the specific record targeted for deletion, allowing an authenticated user with a record-scoped staff role to irreversibly delete any order, customer, or transaction on the site, including records belonging to other staff and outside their assigned scope.
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Analysis
by VulDB Data Team • 10/08/2026
The vulnerability identified in the Appointment Booking Plugin for WordPress prior to version 5.6.5 represents a critical failure in server-side access control mechanisms, specifically manifesting as an insecure direct object reference combined with broken authorization logic. This flaw allows authenticated users who possess staff-level privileges to bypass intended scope restrictions and perform destructive actions on data resources that fall outside their assigned operational boundaries. The core technical deficiency lies in the application's handling of deletion requests for orders, customers, or transactions. When a user initiates a delete operation by providing an identifier for a specific record, the backend logic fails to validate whether the currently authenticated staff member has explicit permission to manage that particular entity. Instead of checking role-based access control policies against the resource owner or scope constraints, the system relies solely on the presence of valid authentication credentials and basic staff status, effectively treating all records as accessible to any logged-in administrator-level user regardless of their specific permissions.
From a technical perspective, this vulnerability aligns with CWE-284, which describes Improper Access Control, and more specifically CWE-639, Authorization Bypass Through User-Controlled Key. The attacker exploits the lack of server-side validation by manipulating the unique identifier associated with the target record. Since the application does not cross-reference the user's assigned scope or role permissions against the ownership attributes of the targeted data object, it proceeds to execute the deletion command immediately upon receiving a valid request from an authenticated session. This behavior creates a situation where privilege escalation is unnecessary; even users with minimal staff privileges can achieve administrative-level destructive capabilities simply by knowing or guessing the identifiers of records they are not authorized to manage. The absence of these checks indicates that the developers relied on client-side restrictions or assumed that lower-privilege roles would naturally be restricted from accessing certain endpoints, which is a fundamental security anti-pattern in web application development.
The operational impact of this vulnerability is severe due to its potential for irreversible data loss and significant disruption to business operations. An attacker with access to the plugin can permanently delete critical customer information, historical order records, and transaction logs without leaving an audit trail that distinguishes between authorized and unauthorized deletions if logging mechanisms are not separately configured. This leads to a complete compromise of data integrity within the context of the appointment booking system. For businesses relying on this plugin for revenue tracking or service scheduling, such actions can result in financial discrepancies, loss of customer history, and operational paralysis as staff lose access to essential records needed to fulfill appointments or process refunds. Furthermore, because the deletion is irreversible without database backups, the recovery effort may be time-consuming and costly, potentially leading to extended downtime and reputational damage if client data is permanently lost.
This vulnerability also facilitates broader security risks beyond simple data destruction. By allowing unauthorized modification of critical records, it undermines the principle of least privilege that underpins secure system design. If an attacker can delete arbitrary records, they may be able to disrupt audit trails or hide malicious activities performed by other compromised accounts. In terms of industry frameworks, this behavior maps directly to MITRE ATT&CK technique T1485, Data Destruction, where the adversary modifies or destroys data and information in a target environment. Additionally, it relates to T1078, Valid Accounts, as the exploitation relies on using legitimate credentials that have been compromised or shared improperly, highlighting how insufficient granular permissions can amplify the impact of credential theft.
To mitigate this vulnerability, immediate action is required by upgrading the Appointment Booking Plugin to version 5.6.5 or later, where these authorization checks have presumably been implemented and validated. In environments where patching cannot occur instantly, administrators should implement compensating controls such as strict input validation on all deletion endpoints to ensure that only users with specific administrative roles can perform bulk deletions or delete records not owned by them. Implementing robust server-side access control middleware that intercepts requests before they reach the business logic layer is essential. This middleware must verify that the authenticated user's role and assigned scope explicitly permit actions on the target resource identifier. Additionally, enabling comprehensive audit logging for all deletion events can aid in forensic analysis and detection of unauthorized activities post-exploitation. Regular security audits focusing on authorization flows are recommended to prevent similar access control bypasses in other parts of the application ecosystem.