CVE-2026-112043
Deferred Deferred - Pending Action

Authorization Bypass in Cal.com Webhook Handler

Publication date: 2026-10-19

Last updated on: 2026-10-19

Assigner: VulDB

Description
A weakness has been identified in calcom cal.com and cal.diy up to 6.2.0. Impacted is the function createWebhookProcedure of the file packages/trpc/server/routers/viewer/webhook/util.ts of the component Webhook Handler. Executing a manipulation of the argument ID can lead to authorization bypass. It is possible to launch the attack remotely. The pull request to fix this issue awaits acceptance.

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Meta Information

Published
2026-10-19
Last Modified
2026-10-19
Generated
2026-10-19
AI Q&A
2026-10-19
EPSS Evaluated
N/A
NVD
CVE-2026-112043
EUVD
EUVD-2026-104051

Affected Vendors & Products

Showing 6 associated CPEs
Vendor Product Version / Range
calcom cal.com 6.0
calcom cal.com 6.1
calcom cal.com 6.2.0
calcom cal.diy 6.0
calcom cal.diy 6.1
calcom cal.diy 6.2.0

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-639 The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.
CWE-285 The product does not perform or incorrectly performs an authorization check when an actor attempts to access a resource or perform an action.

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Executive Summary

This is an Insecure Direct Object Reference (IDOR) vulnerability in Cal.com and Cal.diy versions up to 6.2.0. It allows unauthorized users to bypass authorization checks by manipulating the webhook ID argument in the createWebhookProcedure function. The issue occurs because the system only verifies userId and eventTypeId but fails to check team ownership for team-level webhooks, where userId is null.

Detection Guidance

Check for unauthorized webhook modifications by reviewing webhook logs for unexpected changes to team-level webhooks. Inspect the file packages/trpc/server/routers/viewer/webhook/util.ts for missing team ownership checks in the createWebhookProcedure function. Verify if non-admin users can modify webhooks with null userId values.

Impact Analysis

An attacker could hijack team webhooks to redirect booking event data to their server. This could expose sensitive information like attendee names, emails, phone numbers, time zones, and custom fields. The attack requires only an authenticated user account and knowledge of a webhook UUID.

Compliance Impact

This vulnerability could lead to unauthorized access to personal data, violating GDPR's data protection principles and HIPAA's privacy rules. Exposure of attendee information may result in compliance breaches requiring breach notifications and potential fines.

Mitigation Strategies

Apply the patch from the pull request at https://github.com/calcom/cal.diy/pull/30223. Ensure the middleware in packages/trpc/server/routers/viewer/webhook/util.ts enforces team membership and role checks (ADMIN or OWNER) for team-level webhooks. Review and restrict webhook access to authorized personnel only.

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