Authorization Bypass Through User-Controlled Key

Summary

In versions prior to 1.123.43, 2.0.0-rc.0 prior to 2.20.7 and 2.21.0 prior to 2.21.1, 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. The issue has been fixed in n8n versions 1.123.43, 2.20.7, and 2.21.1. Users should upgrade to one of these versions or later to remediate the vulnerability.