CVE-2026-52839
Summary
Easy!Appointments correctly filters 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.
Root Cause — Step by Step Code Flow
Step 1 — Search correctly enforces provider isolation
The search endpoint filters out appointments belonging to other providers — proving provider isolation is an intended boundary:
// Appointments.php
if ($role_slug === DB_SLUG_PROVIDER) {
foreach ($appointments as $index => $appointment) {
if ((int) $appointment['id_users_provider'] !== (int) $user_id) {
unset($appointments[$index]);
}
}
}
Step 2 — store() only checks generic add permission
The store endpoint checks only whether the caller can add appointments in general — no provider ownership check:
// Appointments.php line 74-152
if (cannot('add', PRIV_APPOINTMENTS)) {
abort(403, 'Forbidden');
}
$appointment = json_decode(request('appointment'), true);
Step 3 — Attacker-controlled id_users_provider saved directly
The controller whitelists and persists the appointment including the attacker-controlled provider ID:
$this->appointments_model->only($appointment, $this->allowed_appointment_fields);
$appointment_id = $this->appointments_model->save($appointment);
No check is performed to verify id_users_provider matches the current session.
Step 4 — Write-befor
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Exploitation outlook
- Low exploitation risk0.15% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 4% of all EPSS-scored CVEs.
Advisory coverage (2)
External references
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