CVE-2026-47769
Deferred Deferred - Pending Action

Unauthenticated Webhook Payload Injection in APIFold

Publication date: 2026-07-23

Last updated on: 2026-07-23

Assigner: GitHub, Inc.

Description
APIFold reads an OpenAPI 3.x or Swagger 2.x specification and generates a live, production-ready MCP server endpoint. Prior to commit 7f19b52280f414f57af2b79a95333d1c8fbeece5, the `/webhooks/:serverSlug/:eventName` endpoint accepts arbitrary unauthenticated JSON and stores it in Redis and the `webhook_events` PostgreSQL table without any signature check or authentication requirement. The root cause is that `createWebhookRouter` is called at `server.ts:188` without a `validators` map, so `receivers.ts:80`'s optional-chaining guard evaluates to `undefined` and the signature-validation block (`receiver.ts:81–95`) is unconditionally skipped. Any unauthenticated network client that knows a valid server slug can inject arbitrary payloads, which are subsequently served as trusted resource state to legitimate MCP clients. Commit 7f19b52280f414f57af2b79a95333d1c8fbeece5 patches the issue.

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Meta Information

Published
2026-07-23
Last Modified
2026-07-23
Generated
2026-07-23
AI Q&A
2026-07-23
EPSS Evaluated
N/A
NVD
CVE-2026-47769
EUVD
EUVD-2026-48338

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
work90210 apifold to 0.2.0 (exc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-306 The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.

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Executive Summary

APIFold is a tool that generates a live MCP server endpoint from an OpenAPI or Swagger specification. This vulnerability allowed unauthenticated users to inject arbitrary JSON payloads into the system via the /webhooks/:serverSlug/:eventName endpoint. The issue occurred because signature validation was skipped due to a missing validators map in the createWebhookRouter function, enabling attackers to store malicious data in Redis and PostgreSQL. The flaw was patched by enforcing mandatory signature validation and implementing a fail-closed approach.

Detection Guidance

Check for unauthorized POST requests to the /webhooks/:serverSlug/:eventName endpoint without valid signatures. Inspect Redis and PostgreSQL webhook_events table for unexpected payloads. Monitor for 401 errors indicating failed signature validation attempts.

Impact Analysis

An attacker could exploit this to inject fake webhook events into your system, which would then be served as trusted data to legitimate clients. This could lead to data integrity issues, unauthorized actions, or persistent compromise of your application's state without requiring authentication or user interaction.

Compliance Impact

This vulnerability could violate compliance requirements for data integrity and access controls. GDPR requires protecting personal data integrity, while HIPAA mandates strict access controls for health information. The lack of authentication and potential for unauthorized data injection could lead to non-compliance with these regulations.

Mitigation Strategies

Update APIFold to a patched version (commit 7f19b52280f414f57af2b79a95333d1c8fbeece5 or later). Configure per-server webhook secrets via the new management UI/API. Ensure validators map is populated when calling createWebhookRouter. Rotate any exposed webhook secrets immediately.

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