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AI agent vulnerability · n8n

CVE-2026-56357: n8n: Webhook Forgery on Github Webhook Trigger

mediumCVSS 4.0 6.3 · 3.1 4.0GHSA-mqpr-49jj-32rc

Impact An attacker who knows the webhook URL of a workflow using the GitHub Webhook Trigger node could send unsigned POST requests and trigger the workflow with arbitrary data. The node did not implement the HMAC-SHA256 signature verification that GitHub provides to authenticate webhook deliveries, allowing any party to spoof GitHub webhook events. Patches The issue has been fixed in n8n versions 2.5.0 and 1.123.15.

Published Feb 26, 2026 · Updated Jul 18, 2026

Affected packages

n8n

Ecosystem
npm
Affected
< 1.123.15
Fixed in
1.123.15
Check
npm ls n8n

n8n

Ecosystem
npm
Affected
>= 2.0.0, < 2.5.0
Fixed in
2.5.0
Check
npm ls n8n

Advisory details

From the GitHub Advisory Database (CC BY 4.0).

Impact

An attacker who knows the webhook URL of a workflow using the GitHub Webhook Trigger node could send unsigned POST requests and trigger the workflow with arbitrary data. The node did not implement the HMAC-SHA256 signature verification that GitHub provides to authenticate webhook deliveries, allowing any party to spoof GitHub webhook events.

Patches

The issue has been fixed in n8n versions 2.5.0 and 1.123.15. Users should upgrade to one of these versions or later to remediate the vulnerability.

Workarounds

If upgrading is not immediately possible, administrators should consider the following temporary mitigations:

  • Limit workflow creation and editing permissions to fully trusted users only.
  • Restrict network access to the n8n webhook endpoint to known GitHub webhook IP ranges.

These workarounds do not fully remediate the risk and should only be used as short-term mitigation measures.

Credited to simonkoeck.

References

How this page is made: the data panel comes from the GitHub Advisory Database, CISA’s KEV catalog, the NVD and FIRST EPSS, and updates twice a day. No analysis has been written for this entry yet. Methodology

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