CVE-2026-48087 open-reception CVE debrief

Who should care

Maintainers and users of OpenReception appointment booking software should assess exposure and apply patches to prevent account takeover. They should verify user ID and email validation in the registration handler and review user passkey rows to prevent unauthorized access.

Why it matters

CVE-2026-48087 allows unauthenticated attackers to perform account takeover by exploiting the registration handler in OpenReception's appointment booking software.

• Unauthenticated attackers can perform account takeover by exploiting the registration handler
• Victim users may be affected if their user IDs and emails are known to attackers
• Maintainers should assess exposure surfaces and verify user ID and email validation
• Patches should be applied to update to version 1.0.2 or later to prevent unauthorized access

Technical summary

The registration handler at `POST /api/auth/register/{userId}` in OpenReception's appointment booking software 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. This allows an unauthenticated attacker to perform account takeover by exploiting the registration handler, as they can submit a registration response with their own authenticator against any victim user's URL. The attacker needs to know the victim's email and userId to perform the attack.

Defensive priority

High priority for maintainers and users of OpenReception appointment booking software to assess exposure and apply patches.

Recommended defensive actions

• Assess exposure by verifying user ID and email validation in the registration handler
• Apply patches to update to version 1.0.2 or later
• Review and update user passkey rows to prevent unauthorized access
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.
• Review compensating controls for exposed systems while remediation is scheduled and verified.
• Check relevant monitoring, detection, and logs for exposed assets that need extra review.
• Track exceptions, retest remediated assets, and close the item only after evidence is documented.

Evidence notes

The CVE record and NVD entry provide details on the vulnerability, which is caused by a lack of validation in the registration handler of OpenReception's appointment booking software. 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. This allows an unauthenticated attacker to request a challenge for their own email, generate a registration response with their

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.