CVE-2026-19416 Overview
CVE-2026-19416 is a broken access control vulnerability in the KiviCare WordPress plugin before version 4.5.4. The plugin fails to verify that the requesting user owns the appointment being modified. Authenticated users with patient-level privileges can cancel and reschedule appointments belonging to other patients. The issue is classified under [CWE-639] Authorization Bypass Through User-Controlled Key, commonly known as an Insecure Direct Object Reference (IDOR).
Critical Impact
Any authenticated patient account can manipulate appointments belonging to other patients, disrupting clinic scheduling and exposing appointment metadata integrity to unauthorized changes.
Affected Products
- KiviCare WordPress plugin versions prior to 4.5.4
- WordPress sites running KiviCare clinic and patient management functionality
- Healthcare and telemedicine deployments relying on KiviCare appointment workflows
Discovery Timeline
- 2026-08-19 - CVE-2026-19416 published to NVD
- 2026-08-19 - Last updated in NVD database
Technical Details for CVE-2026-19416
Vulnerability Analysis
The KiviCare plugin exposes appointment cancellation and rescheduling endpoints to authenticated users. These endpoints accept an appointment identifier from the request but do not validate that the identifier belongs to the authenticated patient. An attacker with a low-privilege patient account can submit another patient's appointment ID and successfully modify or cancel that appointment.
The flaw impacts integrity of appointment records but does not directly expose confidential clinical data or affect service availability at the server level. The attack requires authentication as a patient-level user and user interaction on the endpoint being invoked. The EPSS score of 0.189% reflects a low predicted probability of active exploitation.
Root Cause
The root cause is missing ownership verification on appointment-modifying endpoints. The plugin trusts the appointment ID supplied by the client without cross-checking it against the current user's session identity. This pattern matches the CWE-639 Insecure Direct Object Reference class of authorization defects.
Attack Vector
Exploitation occurs over the network against the WordPress site hosting KiviCare. The attacker registers or authenticates as a patient, enumerates or guesses another patient's appointment ID, and submits a cancel or reschedule request referencing that ID. The vulnerable endpoint processes the request without an ownership check. See the WPScan Vulnerability Analysis for additional technical detail.
No verified public exploit code is available. The vulnerability mechanism is described in prose because no sanitized proof-of-concept has been released.
Detection Methods for CVE-2026-19416
Indicators of Compromise
- Unexpected appointment cancellations or reschedules reported by patients or staff
- HTTP POST requests to KiviCare appointment endpoints containing appointment_id values that do not correspond to the authenticated session user
- Sequential or enumerated appointment IDs appearing in access logs from a single authenticated patient account
Detection Strategies
- Correlate WordPress authentication logs with KiviCare appointment modification actions to identify patients acting on records they do not own
- Alert on any single patient account performing an unusually high volume of appointment modifications within a short time window
- Review database audit trails on the KiviCare appointments table for updated_by or modified_by values that differ from the appointment's owning patient
Monitoring Recommendations
- Enable verbose logging on WordPress REST and admin-ajax endpoints handling KiviCare appointment operations
- Forward WordPress and web server logs to a centralized SIEM for behavioral analysis of authenticated user activity
- Establish a baseline for normal patient appointment modification patterns and alert on deviations
How to Mitigate CVE-2026-19416
Immediate Actions Required
- Upgrade the KiviCare plugin to version 4.5.4 or later on all affected WordPress sites
- Audit recent appointment cancellations and reschedules to identify unauthorized modifications
- Review patient user accounts for signs of suspicious registration or activity patterns
Patch Information
The vendor addressed the missing ownership check in KiviCare version 4.5.4. Site administrators should update through the WordPress plugin dashboard or by replacing the plugin files with the patched release. Verify the installed version in the WordPress admin plugin list after applying the update.
Workarounds
- Restrict patient user registration on the WordPress site until the plugin is patched
- Deploy a web application firewall rule to block requests to KiviCare appointment modification endpoints from non-administrative sessions
- Temporarily disable the KiviCare plugin if patching cannot be performed immediately and appointment integrity is a priority
# Update the KiviCare plugin using WP-CLI
wp plugin update kivicare-clinic-management-system --version=4.5.4
wp plugin list --name=kivicare-clinic-management-system --fields=name,status,version
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
