CVE-2026-48088 in appointment-booking-software
Summary
by MITRE • 08/07/2026
OpenReception's appointment booking software provides an end-to-end encrypted appointment booking platform. Prior to version 1.0.4, the route `POST /api/tenants/{tenantId}/staff/{staffId}/crypto` accepts and stores attacker-controlled ML-KEM-768 public keys against any tenant on the platform without authentication. The handler logs an "Unauthorized crypto key storage attempt" warning when neither a session nor a registration cookie is present, then proceeds to insert the row regardless. The platform's E2E claim that "even administrators cannot view sensitive information" is broken: any unauthenticated network attacker can register themselves as an additional encryption recipient for any tenant's future patient appointments. A second variant of the bug suppresses the unauthorized-warning log entry. The Zod schema makes the `email` field optional. When the request body omits `email` and the request carries no registration cookie, the comparison `registrationEmail === email` becomes `undefined === undefined`, which evaluates to `true`. The handler treats the request as a legitimate registration flow, skips the warning entirely, and stores the row. Successful storage is still recorded as an `[info]` log line, but the security-relevant warning that operators are most likely to monitor or alert on is gone. The `staff_crypto` table has no unique constraint on `user_id`, so an arbitrary number of attacker rows can coexist for the same staff identifier and all return as `is_active=true`. The supplied `staffId` does not need to match any existing user or pending invite. Schema validation on `passkeyId`, `publicKey`, and `privateKeyShare` is also weak: the literal string `<placeholder-base64>` was accepted, indicating no length, format, or cryptographic-validity check beyond field presence. This weakness is independent of the auth bypass but compounds it: a poisoned directory can also be filled with malformed entries that break legitimate booking flows. The injected key is consumed by the public booking flow. After completing the unauthenticated `bootstrap-challenge` and `bootstrap-verify` ceremony as a "patient", the resulting `bookingAccessToken` is accepted by `GET /api/tenants/{id}/appointments/staff-public-keys`, which returns the attacker-controlled keys alongside any legitimate ones. A new appointment encrypts its tunnel key with ML-KEM to all listed recipients, so the attacker becomes a co-recipient of the encryption and can decapsulate the tunnel key with the matching secret. From there, all appointment payloads for that booking are decryptable. Version 1.0.4 patches the issue.
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Analysis
by VulDB Data Team • 08/07/2026
The vulnerability in OpenReception's appointment booking software stems from a critical authentication bypass in the cryptographic key storage endpoint POST /api/tenants/{tenantId}/staff/{staffId}/crypto, which affects versions prior to 1.0.4. This flaw allows unauthenticated attackers to inject malicious ML-KEM-768 public keys into the system without proper authorization, directly undermining the platform's end-to-end encryption claims. The vulnerability manifests through two distinct mechanisms that together create a complete attack vector for unauthorized key insertion. The first mechanism involves the absence of authentication checks during the key storage process, where the system logs an "Unauthorized crypto key storage attempt" warning but still proceeds to store the attacker-controlled public key in the database. This behavior aligns with CWE-285, which addresses authorization issues, and represents a clear violation of the principle of least privilege. The second variant of this vulnerability occurs when the request body omits the email field entirely, causing the comparison `registrationEmail === email` to evaluate as true since both values are undefined, effectively bypassing all authentication checks and suppressing the warning logs that security teams rely on for monitoring suspicious activities.
The technical implementation of this vulnerability is exacerbated by weak schema validation practices within the system's Zod validation layer. The email field is marked as optional, which creates a dangerous condition where missing email fields can be interpreted as legitimate registration flows. This design flaw enables attackers to bypass authentication entirely while avoiding detection through the suppression of warning messages that would normally trigger alerts. The absence of unique constraints on the user_id field in the staff_crypto table compounds the issue by allowing unlimited entries for the same staff identifier, all of which are marked as active. Furthermore, the system does not validate the integrity of cryptographic keys during storage, accepting literal strings such as empty values for passkeyId, publicKey, and privateKeyShare fields, indicating a complete lack of format, length, or cryptographic validity checks. This weakness, categorized under CWE-20, represents a fundamental failure in input validation that allows malformed entries to be stored in the system.
The operational impact of this vulnerability is severe and directly compromises the integrity of the end-to-end encryption system. An attacker can register themselves as an additional encryption recipient for any tenant's future patient appointments, effectively breaking the security model that claims even administrators cannot view sensitive information. The attack chain begins with the unauthenticated insertion of malicious keys, followed by the exploitation of the public booking flow where attackers complete bootstrap-challenge and bootstrap-verify ceremonies as patients. This allows them to obtain a bookingAccessToken which can then be used to request staff-public-keys from GET /api/tenants/{id}/appointments/staff-public-keys. The attacker-controlled keys are then included in the list alongside legitimate ones, enabling them to participate in the encryption process for future appointments. When new appointments are created, their tunnel keys are encrypted using ML-KEM to all listed recipients, including the attacker's malicious key. This provides the attacker with the capability to decapsulate the tunnel key and subsequently decrypt all appointment payloads for that booking, effectively breaking the end-to-end encryption guarantee. The attack aligns with ATT&CK technique T1566, which involves social engineering through phishing or other means, in this case through authentication bypass rather than traditional phishing methods.
The mitigation implemented in version 1.0.4 addresses all aspects of this vulnerability by enforcing proper authentication checks before allowing key storage operations to proceed. The fix ensures that unauthorized attempts are properly rejected and that warning messages are consistently logged for monitoring purposes. Additionally, the update strengthens schema validation to enforce cryptographic key integrity checks and implements unique constraints on user_id fields to prevent unlimited duplicate entries. These changes align with security best practices outlined in NIST SP 800-53 and ISO/IEC 27001 standards for access control and input validation. The system now properly validates all cryptographic parameters, ensuring that only valid keys are accepted during storage operations, which prevents the insertion of malformed entries that could disrupt legitimate booking flows. This comprehensive patch restores the platform's end-to-end encryption guarantees by ensuring that only authorized entities can modify the key storage configuration for staff members, thereby protecting patient data from unauthorized access and maintaining the integrity of the encryption infrastructure.