n8n before 2.45.5, 2.46.x before 2.46.1, and 3.x before 3.0.1 contains a flaw in the OAuth2 credential callback of the dynamic-credential connect flow, which does not verify that the completing browser belongs to the user who started the flow. Members with access to a resolvable OAuth2 credential can send the provider authorization URL to a victim; if the victim consents without an active n8n session, the victim's tokens are stored under the member's identity, letting the member's workflows act as the victim.