OpenReception appointment-booking-software up to 1.0.1 Registration /api/auth/register userId assertion

Summaryinfo

A vulnerability, which was classified as critical, has been found in OpenReception appointment-booking-software up to 1.0.1. This impacts an unknown function of the file /api/auth/register of the component Registration Handler. Performing a manipulation of the argument userId results in assertion. This vulnerability is known as CVE-2026-48087. Remote exploitation of the attack is possible. No exploit is available.

Detailsinfo

A vulnerability was found in OpenReception appointment-booking-software up to 1.0.1. It has been classified as critical. This affects an unknown functionality of the file /api/auth/register of the component Registration Handler. The manipulation of the argument userId with an unknown input leads to a assertion vulnerability. CWE is classifying the issue as CWE-617. The product contains an assert() or similar statement that can be triggered by an attacker, which leads to an application exit or other behavior that is more severe than necessary. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

OpenReception's appointment booking software provides an end-to-end encrypted appointment booking platform. Prior to version 1.0.2, the registration handler at `POST /api/auth/register/{userId}` validates the relationship between the WebAuthn challenge and the registration cookie's email but never validates that the `userId` in the URL belongs to that email. An unauthenticated attacker requests a challenge for their own email, generates a registration response with their own authenticator, and submits it against any victim user's URL. The challenge-vs-cookie email match passes, the WebAuthn ceremony validates, and `addPasskey` writes the attacker's credential into the victim's `user_passkey` rows. The next victim-email login accepts a passkey assertion from the attacker's authenticator and issues a session as the victim. User IDs are not strictly secret on this platform, but the exact set of exposure surfaces should be assessed by the maintainers. Staff-list endpoints return user IDs to authenticated tenant members per the route signature; live verification of all exposure surfaces (whether user IDs leak through any unauthenticated route, through invite-confirmation URLs, or through other administrative views) is part of the pending live PoC. Where the attacker knows the victim's email and userId, the analysis below becomes account takeover. Version 1.0.2 fixes the issue.

It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-48087 since 05/20/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details of the vulnerability are known, but there is no available exploit.

Upgrading to version 1.0.2 eliminates this vulnerability.

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Productinfo

Type

• Appointment Software

Vendor

• OpenReception

Name

• appointment-booking-software

Version

• 1.0.0
• 1.0.1

CPE 2.3info

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• 🔒

CPE 2.2info

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• 🔒

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