n8n: Cross-user Authorization Bypass in Dynamic Credential OAuth Endpoints

n8n is an open source workflow automation platform. Prior to 1.123.43, 2.22.1, and 2.20.7, the OAuth1 and OAuth2 credential reconnect endpoints authorized access using credential:read rather than credential:update. An authenticated user with read-only access to a shared credential could initiate an OAuth reconnect flow and overwrite the stored token material for that credential with tokens bound to an external account they control. Workflows relying on the affected credential would subsequently execute under the attacker's OAuth identity, enabling data exfiltration to attacker-controlled external services and persistent takeover of shared integrations. This vulnerability is fixed in 1.123.43, 2.22.1, and 2.20.7.