Webhook Authentication for SalesForce

We created a webhook in Contentful that on publish, calls an end point in SalesForce. This endpoint requires that a user name and password be provided, when authenticated, it returns a session ID that we use to call back the same endpoint and run the actual code in SalesForce. Can webhooks in Contentful support the login in, getting the session ID and then callback (to the same end point) with the session ID?