n8n before 1.123.15 and 2.5.0 contains a webhook forgery vulnerability in the GitHub Webhook Trigger node that fails to implement HMAC-SHA256 signature verification.
Date: 2026-06
Affected: n8n/n8n
Attack vector: other
Category: vulnerability-disclosure
Severity: Medium
CVE: CVE-2026-56357
CWE: CWE-290
CVSS: 4 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N)

n8n before 1.123.15 and 2.5.0 contains a webhook forgery vulnerability in the GitHub Webhook Trigger node that fails to implement HMAC-SHA256 signature verification. Attackers who know the webhook URL can send unsigned POST requests to trigger workflows with arbitrary data, spoofing GitHub webhook events.


Mitigations:

Architectural layers (MAESTRO):