What is the CVSS score of CVE-2026-34577?

CVE-2026-34577 has a CVSS 3.1 base score of 8.6 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N. EPSS exploitation probability: 0.1%.

Which versions of Postiz App are affected by CVE-2026-34577?

Postiz AI versions before 2.21.3 contain an unauthenticated server-side request forgery vulnerability that allows attackers to access internal network resources and cloud metadata endpoints, posing…. A patch is available.

How to fix or mitigate CVE-2026-34577?

Within 24 hours: identify all Postiz instances in your environment and document current versions. Within 7 days: upgrade all Postiz deployments to version 2.21.3 or later; verify the /public/stream endpoint is accessible only to authenticated users post-patch. Within 30 days: conduct network segmentation review to restrict Postiz server access to cloud metadata endpoints (169.254.169.254 for AWS, etc.) and implement WAF rules to block requests to internal IP ranges through the proxy endpoint.

Postiz App CVE-2026-34577

EUVD-2026-18448 HIGH

Server-Side Request Forgery (SSRF) (CWE-918)

2026-04-02 GitHub_M

SSRF Postiz App Gitroomhq

8.6

CVSS 3.1 · Vendor: GitHub_M

Severity by source

Vendor (GitHub_M) PRIMARY

8.6 HIGH

AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N

Primary rating from Vendor (GitHub_M) · only source for this CVE.

CVSS VectorVendor: GitHub_M

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Changed

Confidentiality

High

Integrity

None

Availability

None

Lifecycle Timeline

Analysis Updated

Apr 16, 2026 - 06:08 EUVD-patch-fix

executive_summary

Re-analysis Queued

Apr 16, 2026 - 05:29 backfill_euvd_patch

patch_released

Patch available

Apr 16, 2026 - 05:29 EUVD

2.21.3

EUVD ID Assigned

Apr 02, 2026 - 17:30 euvd

EUVD-2026-18448

Analysis Generated

Apr 02, 2026 - 17:30 vuln.today

CVE Published

Apr 02, 2026 - 17:24 nvd

HIGH 8.6

DescriptionCVE.org

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.

AnalysisAI

Server-side request forgery in Postiz AI social media scheduling tool (versions < 2.21.3) allows unauthenticated remote attackers to read internal network resources and cloud metadata endpoints through the /public/stream proxy endpoint. The vulnerability bypasses trivial .mp4 validation via query parameters or URL fragments, enabling unauthorized access to internal services without authentication. No public exploit identified at time of analysis, but CVSS 8.6 reflects high confidentiality impact with network-level attack vector and low complexity. EPSS data not available, but the combination of no authentication requirement and cloud metadata access risk makes this a priority for organizations running Postiz in cloud environments.

Technical ContextAI

This is a classic Server-Side Request Forgery (CWE-918) vulnerability in Postiz's PublicController component. The /public/stream endpoint was designed to proxy video content (hence the .mp4 validation), but implements only suffix-based URL filtering that checks url.endsWith('mp4'). This validation is fundamentally flawed because HTTP URLs can contain arbitrary query strings (e.g., http://169.254.169.254/latest/meta-data?.mp4) or fragments (e.g., http://internal-service/admin#.mp4) that satisfy the suffix check while pointing to non-video resources. The endpoint acts as an open HTTP proxy, forwarding requests to attacker-controlled destinations and returning full responses. In cloud environments, this enables access to instance metadata services (AWS 169.254.169.254, GCP metadata.google.internal, Azure 169.254.169.254) which can expose credentials, API keys, and configuration data. The affected product per CPE data is gitroomhq:postiz-app versions prior to 2.21.3.

RemediationAI

Upgrade immediately to Postiz version 2.21.3 or later, which contains patches for the SSRF vulnerability. The patched release is available at https://github.com/gitroomhq/postiz-app/releases/tag/v2.21.3 and includes proper URL validation that prevents bypassing the .mp4 suffix check. If immediate patching is not possible, implement network-level controls as temporary mitigation: configure egress filtering to block the Postiz application server from accessing internal networks and cloud metadata endpoints (169.254.169.254, metadata.google.internal, etc.), and place the application behind a web application firewall with SSRF protection rules. Additionally, restrict access to the /public/stream endpoint at the network perimeter if the streaming functionality is not required for your deployment. Review application logs for suspicious requests to the /public/stream endpoint with unusual URL parameters to identify potential exploitation attempts. After patching, verify the fix by attempting to access internal resources through the endpoint to confirm proper validation is enforced.