n8n Has Authorization Bypass in OAuth Callback via N8N_SKIP_AUTH_ON_OAUTH_CALLBACK

Impact

When the N8N_SKIP_AUTH_ON_OAUTH_CALLBACK environment variable is set to true, the OAuth callback handler skips ownership verification of the OAuth state parameter. This allows an attacker to trick a victim into completing an OAuth flow against a credential object the attacker controls, causing the victim's OAuth tokens to be stored in the attacker's credential. The attacker can then use those tokens to execute workflows in their name.

• This issue only affects instances where N8N_SKIP_AUTH_ON_OAUTH_CALLBACK=true is explicitly configured (non-default).

Patches

The issue has been fixed in n8n version 2.8.0. Users should upgrade to this version or later to remediate the vulnerability.

Workarounds

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

• Avoid enabling N8N_SKIP_AUTH_ON_OAUTH_CALLBACK=true unless strictly required.
• Restrict access to the n8n instance to fully trusted users only.

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