The report
A Slack Trigger is usually treated as an event arriving from a trusted service. The disclosed n8n weakness occurred when a configured Slack signing secret was absent and the trigger could accept unauthenticated, forged webhook requests. In a vulnerable workflow, attacker-supplied event fields could then flow into downstream Slack file retrieval using credentials already held by the automation.
The attacker's power comes from impersonating the event source, not from gaining the OAuth credential directly in advance. Depending on the rest of the workflow, the result could include credential-bearing requests or server-side fetching, but the security advisory is not evidence that all n8n installations exposed files. The specific Case keeps configuration prerequisites and observed results distinct from potential impact.
An upgrade check should send a harmless forged event to the actual public trigger and confirm rejection before any agent, file fetch or credentialed action is invoked. Turning on signature verification only after the event has already entered the workflow is not equivalent to authenticating it at the webhook boundary.