VulnerabilityDeferred

CVE-2026-48087

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.

CRITICAL 9.8EPSS 0.46%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (0.46%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

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 3.1: 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS: 0.46% probability · 39th percentile
CISA KEV: Not listed
Weakness: CWE-287
Source: security-advisories@github.com

References

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.