CVE-2026-34577 Postiz: Unauthenticated Full-Read SSRF via /public/stream Endpoint with Trivially Bypassable Extension Check

High 8.6 Published 2 Apr 2026 Updated 3 Apr 2026

Unauthenticated attackers can read internal network resources via Server-Side Request Forgery in Postiz due to insufficient URL validation.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2026-34577?

CVE-2026-34577 is a high-severity server-side request forgery vulnerability in gitroomhq postiz-app, published on 2 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

Postiz is an AI social media scheduling tool. Prior to version 2.21.3, the GET /public/stream endpoint in PublicController accepts a user-supplied url query parameter and proxies the full HTTP response back to the caller. The only validation is url.endsWith('mp4'), which is trivially bypassable by appending .mp4 as a query parameter value or URL fragment. The endpoint requires no authentication and has no SSRF protections, allowing an unauthenticated attacker to read responses from internal services, cloud metadata endpoints, and other network-internal resources. This issue has been patched in version 2.21.3.

Weakness: CWE-918

Which versions are affected by CVE-2026-34577?

It affects 1 product.

Products include Gitroom Postiz.

How do I fix CVE-2026-34577?

No fix has been published for CVE-2026-34577 yet. Limit exposure of the affected software until one is available.

Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.

Is CVE-2026-34577 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-34577 exists.

Sources

Also known as GHSA-mv6h-v3jg-g539.