Executive brief
Postiz, an AI-powered social media scheduling tool, contains a security flaw in its public media streaming component. An unauthenticated attacker can use this flaw to trick the server into accessing and returning data from internal systems that are not supposed to be reachable from the internet. This could lead to the theft of sensitive cloud credentials, exposure of internal databases, and unauthorized access to private company data.
Technical details
A Server-Side Request Forgery (SSRF) vulnerability exists in the `PublicController` of Postiz due to insufficient validation of the `url` parameter in the `GET /public/stream` endpoint. The application attempts to restrict requests by checking if the URL ends with '.mp4', but this is easily bypassed by appending '.mp4' as a dummy query parameter or fragment (e.g., `http://internal-service/.mp4`). Because the application proxies the full HTTP response back to the requester without authentication or network-level restrictions, an attacker can perform full-read SSRF. This allows for the retrieval of sensitive data from internal network resources, such as cloud metadata services (AWS/GCP/Azure) and internal databases. The vulnerability is resolved in version 2.21.3.
Affected products
- gitroomhq Postiz < 2.21.3
Timeline
- 2026-03-28: disclosed: Initial report received by vendor
- 2026-03-29: patched: Version 2.21.3 released with security fix
- 2026-04-02: advisory: CVE-2026-34577 published