The vulnerability allows any user to supply a URL to the /public/stream endpoint and have the application fetch the full HTTP response, returning it to the requester. The only validation is a weak check that the URL ends with ".mp4", which can be trivially bypassed by adding ".mp4" as a query parameter or fragment. Because the endpoint is unauthenticated and lacks SSRF safeguards, an attacker can read data from internal services, cloud metadata endpoints, and other network resources that are reachable from the host. This weakness is a Server Side Request Forgery, allowing confidentiality compromise of internal systems.

Gitroomhq’s Postiz application, specifically versions earlier than 2.21.3, is affected. The issue is fixed in release 2.21.3 and any later version.

The CVSS score of 8.6 indicates a high severity flaw. The EPSS score is below 1%, suggesting a low current probability of exploitation, and the vulnerability is not listed in the CISA KEV catalog. Since the endpoint requires no authentication and imposes no SSRF prevention, the attack can be carried out by anyone with access to the application’s public interface, making the exposure straightforward for an adversary who discovers it.