CVE-2026-52839 in Easy Appointments
Summary
by MITRE • 07/14/2026
Easy!Appointments is a self hosted appointment scheduler. Versions prior to 1.6.0 correctly filter provider-scoped appointments in the `appointments/search` response, proving that provider isolation is an intended security boundary. However, the direct mutation endpoints `appointments/store` and `appointments/update` only check generic appointment privileges and never verify that the submitted `id_users_provider` belongs to the current session. A normal authenticated provider can inject new appointments into another provider's schedule via `store`, or reassign existing appointments into a foreign provider's calendar via `update`. The `store` path contains an additional write-before-crash bug: the unauthorized row is committed to the database before the controller crashes on a type error, so the attacker receives an error response while the foreign appointment is already persisted. Version 1.6.0 patches the issue.
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Analysis
by VulDB Data Team • 07/15/2026
The vulnerability in Easy!Appointments prior to version 1.6.0 represents a critical authorization flaw that undermines the application's core security model for provider isolation. This issue manifests as a privilege escalation vulnerability where authenticated providers can manipulate appointments belonging to other providers through direct mutation endpoints. The system correctly implements filtering for read operations in the `appointments/search` endpoint, establishing that provider boundaries are intentionally enforced for data retrieval. However, the inconsistency in access control validation becomes apparent when examining the write operations `appointments/store` and `appointments/update`. These endpoints fail to validate that the `id_users_provider` parameter matches the authenticated user's session, creating a fundamental security gap where providers can inject or modify appointments outside their designated scope.
The technical implementation flaw stems from incomplete input validation and authorization checks within the mutation endpoints. When processing appointment creation via `store`, the application commits the database record before performing the necessary type checking that would normally occur during request validation. This write-before-crash behavior creates a race condition where unauthorized data persistence occurs despite subsequent error responses to the attacker. The vulnerability enables attackers to inject appointments into foreign provider calendars through direct manipulation of the `id_users_provider` field, effectively bypassing the intended multi-tenant security boundaries. Similarly, the `update` endpoint allows existing appointments to be reassigned from one provider's schedule to another, completely undermining the provider isolation mechanism that should protect each user's appointment data.
From a cybersecurity perspective, this vulnerability aligns with CWE-285 (Improper Authorization) and represents a classic case of insufficient access control validation. The flaw operates at the application logic level rather than a simple configuration issue, making it particularly dangerous as it requires no special privileges beyond normal provider authentication. The operational impact extends beyond simple data manipulation to include potential service disruption, privacy violations, and compliance breaches in regulated environments where patient appointment data must remain isolated between providers. Attackers could exploit this vulnerability to create false appointments, disrupt scheduling for other providers, or potentially access sensitive information through the injection of malicious appointment data. This type of authorization bypass is categorized under ATT&CK technique T1078 (Valid Accounts) and T1496 (Resource Hijacking), as it leverages legitimate authentication credentials to perform unauthorized actions against system resources.
The patch implemented in version 1.6.0 addresses this vulnerability by enforcing proper authorization checks on the `id_users_provider` field within both mutation endpoints, ensuring that all appointment modifications are validated against the authenticated user's session context. This fix aligns with security best practices for multi-tenant applications and implements proper input validation to prevent unauthorized data manipulation. Organizations using Easy!Appointments should prioritize immediate upgrade to version 1.6.0 or later to remediate this vulnerability. Additionally, system administrators should monitor audit logs for any suspicious appointment creation or modification activities that might indicate exploitation attempts. The vulnerability demonstrates the importance of consistent security controls across all application endpoints, particularly in healthcare and service scheduling applications where data isolation is critical for maintaining privacy and regulatory compliance.