CVE-2026-86073: n8n: Per-Resource OAuth Consent Bypass via Unbound Refresh Token Resource Substitution
n8n is an open source workflow automation platform. Prior to 2.37.7 and 2.38.1, the OAuth token endpoint bound an authorization code's first access token to the consented resource but did not bind its refresh token. Refreshing checked only that the requested resource was registered, not that it matched the original grant. An OAuth client approved for one workflow could substitute a different workflow URL in the resource parameter and obtain a valid token for an unapproved workflow accessible to the consenting user. This issue is fixed in versions 2.37.7 and 2.38.1.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 2.37.7Patch n8n: Per-Resource OAuth Consent Bypass via Unbound Refresh Token Resource Substitution - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 2.38.1Patch n8n: Per-Resource OAuth Consent Bypass via Unbound Refresh Token Resource Substitution
Event History
Frequently Asked Questions
Which deployments are affected?
n8n versions earlier than 2.37.7 and 2.38.1 are affected. The issue concerns OAuth clients using authorization-code grants with refresh tokens and per-resource consent.
What does an attacker need to exploit this issue?
An OAuth client must first be approved for one workflow by a consenting user. It can then use the refresh token while substituting the URL of a different registered workflow that the user can access.
What is the impact of successful exploitation?
The client can obtain a valid token for a workflow that was not included in the user's original consent. Access is limited to other registered workflow resources accessible to that same user.
What should be done if upgrading is not immediately possible?
The provided information does not identify a configuration workaround. Restrict or review OAuth clients that can obtain refresh tokens and have access to multiple workflow resources until upgrading to a fixed version.