CVE-2026-34577
Published: 02 April 2026
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…
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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.
Mitigating Controls (NIST 800-53 r5)AI
Requires validation of user-supplied URL inputs to prevent bypassable checks that enable SSRF exploitation.
Enforces information flow control policies to block server-initiated requests to internal services, localhost, or private network resources.
Monitors and controls communications at system boundaries to restrict outbound proxy requests to unauthorized internal endpoints.
Security SummaryAI
CVE-2026-34577 is a server-side request forgery (SSRF) vulnerability, classified under CWE-918, affecting Postiz, an AI-powered social media scheduling tool. In versions prior to 2.21.3, the unauthenticated GET /public/stream endpoint in the PublicController accepts a user-supplied "url" query parameter and proxies the full HTTP response back to the caller. The sole validation checks if the URL ends with ".mp4", which can be easily bypassed by appending ".mp4" to the query parameter value or as a URL fragment.
Unauthenticated attackers can exploit this vulnerability remotely with low complexity and no privileges required, as indicated by the CVSS v3.1 base score of 8.6 (AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N). By crafting a malicious URL that passes the weak validation, attackers can force the server to make requests to arbitrary internal services, cloud metadata endpoints like those on localhost or private IPs, and other network-internal resources, potentially leaking sensitive data through the proxied responses.
The vulnerability has been patched in Postiz version 2.21.3. Security practitioners should upgrade to this version or later. Additional details are available in the GitHub security advisory at https://github.com/gitroomhq/postiz-app/security/advisories/GHSA-mv6h-v3jg-g539 and the release notes at https://github.com/gitroomhq/postiz-app/releases/tag/v2.21.3.
Details
- CWE(s)
Affected Products
AI Security AnalysisAI
- AI Category
- Other AI Platforms
- Risk Domain
- N/A
- OWASP Top 10 for LLMs 2025
- None mapped
- MITRE ATLAS Techniques
- None mapped
- Classification Reason
- Matched keywords: ai
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
SSRF in unauthenticated public-facing endpoint (T1190) allows attackers to force server requests to internal resources including cloud metadata endpoints (T1522), leaking sensitive data.