Plane is an open-source project management tool. Prior to 1.4.0, the webhook delivery task in apps/api/plane/bgtasks/webhook_task.py calls requests.post() without allow_redirects=False and does not validate redirect targets. validate_url() blocks private, loopback, link-local, and reserved addresses in the original webhook URL, but the final URL reached after one or more redirects is not checked. A user who can create a workspace can register a webhook pointing to an attacker-controlled public endpoint that returns a 302 redirect to an internal address. The Plane worker then fetches internal resources, including cloud metadata, and stores the response body in webhook_logs, where the attacker can retrieve it through the workspace webhook-logs API. This issue is fixed in 1.4.0.
The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.