CVE-2026-48087

Received Received - Intake

WebAuthn Authentication Bypass in OpenReception

Publication date: 2026-08-06

Last updated on: 2026-08-06

Assigner: GitHub, Inc.

Description

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.

CVSS Scores

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Meta Information

Published

2026-08-06

Last Modified

2026-08-06

Generated

2026-08-07

AI Q&A

2026-08-07

EPSS Evaluated

N/A

NVD

CVE-2026-48087

Affected Vendors & Products

Vendor	Product	Version / Range
openreception	appointment_booking_software	to 1.0.2 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-287	When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.

Attack-Flow Graph

Executive Summary

This vulnerability is an account takeover flaw in OpenReception's appointment booking software before version 1.0.2. An unauthenticated attacker can register a passkey for any user by exploiting improper validation of the userId in the registration URL against the email in the session cookie. The attacker requests a challenge for their own email, generates a registration response, and submits it to the victim's userId URL. The system incorrectly allows this, linking the attacker's authenticator to the victim's account. This grants the attacker access to the victim's account during login.

Detection Guidance

This vulnerability requires checking for unauthorized passkey registrations in the victim's user_passkey rows. Inspect database entries for user_passkey tables to detect unexpected credentials linked to victim user IDs. Review logs for POST /api/auth/register/{userId} requests with mismatched email and userId parameters.

Impact Analysis

If you use OpenReception's software before version 1.0.2, an attacker could take over your account by registering their authenticator under your userId. This could allow them to access your appointments, personal data, or perform actions on your behalf. The impact depends on the sensitivity of the data managed by the software.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive user data, which may violate GDPR's data protection requirements and HIPAA's safeguards for protected health information. Unauthenticated attackers could impersonate victims, potentially exposing personal or health-related data.

Mitigation Strategies

Upgrade OpenReception's appointment booking software to version 1.0.2 or later to address the vulnerability.

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