n8n before 2.29.8 and 2.30.x before 2.30.1 (affected from 2.27.0, when the OAuth 2.1 consent and token-issuance flow was introduced) does not verify that the authenticated user has access to the workflow referenced as the OAuth resource. On instances with at least one active MCP Server Trigger workflow configured with n8n OAuth2 authentication, a member-level user can register an OAuth client, self-approve consent for another user's workflow, and obtain a valid token. The workflow then runs in the owner's project context with the owner's stored credentials, and the attacker can set tool inputs and read outputs (potentially including data from the owner's connected integrations), breaking user and project isolation.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Attack Requirements
Present
Additional conditions required
Privileges Required
Low
Basic privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
Low
Partial data leak
Integrity
Low
Partial data modification
Availability
None
No disruption
CVSS Vector v4.0
Weakness Type (CWE)
Vulnerable Products 4
| Configuration | From (including) | Up to (excluding) |
|---|---|---|
|
N8n N8n
cpe:2.3:a:n8n:n8n:*:*:*:*:community:node.js:*:*
|
2.27.0
|
2.29.8
|
|
N8n N8n
cpe:2.3:a:n8n:n8n:*:*:*:*:enterprise:node.js:*:*
|
2.27.0
|
2.29.8
|
|
N8n N8n
cpe:2.3:a:n8n:n8n:2.30.0:*:*:*:community:node.js:*:*
|
— | — |
|
N8n N8n
cpe:2.3:a:n8n:n8n:2.30.0:*:*:*:enterprise:node.js:*:*
|
— | — |