CVE-2026-19416 in KiviCare Plugin
Summary
by MITRE • 08/19/2026
The KiviCare WordPress plugin before 4.5.4 does not verify that the requesting user owns the appointment being modified, allowing authenticated patient-level users to cancel and reschedule other patients' appointments.
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Analysis
by VulDB Data Team • 08/19/2026
The vulnerability identified in versions of the KiviCare WordPress plugin prior to version 4.5.4 represents a critical failure in server-side access control logic, specifically manifesting as an Insecure Direct Object Reference (IDOR). This flaw arises from the application's inability to properly validate that the authenticated user initiating a request possesses ownership or administrative privileges over the specific appointment resource being targeted for modification. Instead of binding the action to the session context and verifying entity ownership against the database records, the plugin relies on client-supplied identifiers without sufficient server-side authorization checks. This architectural oversight allows any authenticated user with even minimal patient-level access to interact directly with API endpoints or form submissions that manipulate appointment data, bypassing intended permission boundaries entirely.
From a technical perspective, this vulnerability enables unauthorized actors to perform state-changing operations such as canceling and rescheduling appointments belonging to other patients. The operational impact of this flaw extends beyond mere privacy violations; it disrupts the integrity of medical scheduling systems which are critical for healthcare providers. Malicious users can exploit this weakness to cause denial of service by repeatedly cancelling valid appointments, thereby creating confusion in clinic operations and potentially depriving legitimate patients of their scheduled care times. Furthermore, the ability to reschedule other patients' appointments introduces significant risks regarding patient safety and data confidentiality, as it may lead to missed diagnoses or treatments if a victim is not present at the newly assigned time slot without their knowledge.
This type of vulnerability aligns closely with CWE-284, which describes Improper Access Control, where insufficient verification prevents users from accessing resources they are not authorized for. In terms of offensive security frameworks, this behavior maps to MITRE ATT&CK technique T1078, specifically the Valid Accounts sub-category, as it leverages legitimate credentials to perform unauthorized actions within an application's functional scope. The exploitation does not require complex injection techniques or privilege escalation beyond what is already granted by a standard patient login, making it highly accessible and dangerous in environments where user trust levels are assumed rather than strictly enforced through cryptographic or logical verification mechanisms.
To mitigate this vulnerability, developers must implement robust server-side authorization checks for all endpoints that modify appointment data. This involves ensuring that every request to cancel or reschedule an appointment includes a validation step that compares the authenticated user's identity against the owner field of the target appointment record in the database. If the identities do not match and the user lacks explicit administrative privileges, the system must reject the request with an appropriate error code rather than processing it. Additionally, implementing session-based token verification for all state-changing operations can help prevent cross-site request forgery attacks that might otherwise facilitate this exploitation. Regular security audits focusing on object-level access control are essential to identify and rectify similar logic flaws in web applications handling sensitive personal information.