n8n before 1.123.83, 2.41.4, and 2.42.1 Slack Token Exfiltration via Slack Trigger

Summary

n8n before 1.123.83, 2.41.4, and 2.42.1 contains a server-side request forgery vulnerability in the Slack Trigger webhook that allows unauthenticated attackers to exfiltrate Slack tokens by bypassing signature verification when no signing secret is set. Attackers who know the webhook URL can name a file to download, causing the node to send the workspace access token to an attacker host and return the response.

Remediation

1. Inventory every n8n-io n8n deployment, including staging.
2. Upgrade n8n-io n8n to the fixed version for your release line, listed under Affected versions.
3. Confirm the running version after the upgrade.

References

• Advisoryhttps://github.com/n8n-io/n8n/security/advisories/GHSA-3c3p-5959-3ghr
• Advisoryhttps://www.vulncheck.com/advisories/n8n-before-1.123.83-2.41.4-and-2.42.1-slack-token-exfiltration-via-slack-trigger