What the vulnerability does
01Description
In Zammad 6.4.x before 6.4.2, SSRF can occur. Authenticated admin users can enable webhooks in Zammad, which are triggered as POST requests when certain conditions are met. If a webhook endpoint returned a redirect response, Zammad would follow it automatically with another GET request. This could be abused by an attacker to cause GET requests for example in the local network.
