What is the CVSS score of EUVD-2026-21571?

EUVD-2026-21571 has a CVSS 3.1 base score of 8.2 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:L. EPSS exploitation probability: 0.0%.

How to fix or mitigate EUVD-2026-21571?

Within 24 hours: Identify all Postiz deployments and confirm running version via admin console or deployment logs. Within 7 days: Upgrade Postiz to version 2.21.5 or later on all affected instances; test streaming functionality post-upgrade in non-production environment first. Within 30 days: Audit logs for /api/public/stream endpoint access patterns during the vulnerability window and implement network segmentation to restrict Postiz server outbound access to only required external services.

Postiz App EUVD-2026-21571

Q: Which versions of Postiz App are affected by EUVD-2026-21571?

Postiz versions before 2.21.5 contain an unauthenticated server-side request forgery vulnerability that allows attackers to access internal network resources and exfiltrate sensitive data through the…. A patch is available.

| CVE-2026-40168 HIGH

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

2026-04-10 GitHub_M

SSRF Postiz App Gitroomhq

8.2

CVSS 3.1 · Vendor: GitHub_M

View

Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

Access

Supply public URL passing validation
Exploit

Server follows HTTP redirect
Execution

Access internal resource
Impact

Exfiltrate sensitive data or cause denial of service

Vulnerability Assessment

Weakness	CWE CWE-918 OWASP Top 10:2025 A01:2025 - Broken Access Control ASVS 5.0 V4 - API and Web Service URL allowlisting, SSRF prevention MITRE ATT&CK 2 techniques across 2 tactics: Initial Access, Credential Access The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. Sign in to read
Exploitation Conditions	Postiz versions prior to 2.21.5. Remote unauthenticated attacker exploits /api/public/stream endpoint by supplying a public HTTPS URL that redirects to internal resources. No user interaction required. Default configurations vulnerable.
Impact	CVSS 8.2 reflects high-impact confidentiality compromise via unauthenticated SSRF. Attack vector is network-accessible with low complexity. Blast radius includes internal resource exposure (databases, metadata services, cloud credentials). Critical for internet-facing Postiz deployments. EPSS data unavailable; GitHub advisory confirms vendor patched in 2.21.5.
Exploit ScenarioDerived	Attacker submits crafted public URL to /api/public/stream endpoint passing initial validation, then leverages HTTP redirect chain to reach internal target (e.g., 169.254.169.254 for cloud metadata). Server follows redirect, exfiltrating sensitive data. No authentication required.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).

Patch available 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Apr 10, 2026

Server-side request forgery in Postiz (gitroomhq postiz-app) versions prior to 2.21.5 allows unauthenticated remote attackers to access internal network resources and exfiltrate sensitive data via the /api/public/stream endpoint. The vulnerability exploits inadequate redirect validation: attackers supply public HTTPS URLs that pass initial validation but redirect server requests to private internal hosts, bypassing security controls. High confidentiality impact with potential service disruption. No public exploit identified at time of analysis.

RemediationAI

Vendor-released patch: upgrade to Postiz version 2.21.5 or later, which implements redirect destination validation to prevent SSRF via the /api/public/stream endpoint. Upstream commit 30e8b777098157362769226d1b46d83ad616cb06 addresses redirect chain validation. Organizations unable to upgrade immediately should implement network egress filtering to block server-initiated requests to internal IP ranges and apply web application firewall rules restricting /api/public/stream access. Consult vendor security advisory at https://github.com/gitroomhq/postiz-app/security/advisories/GHSA-34w8-5j2v-h6ww for technical details. Release notes available at https://github.com/gitroomhq/postiz-app/releases/tag/v2.21.5

Affected VersionsENISA

postiz-app < 2.21.5

Affected Packages

euvd postiz_app fix: 2.21.5

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

CWE-918 SSRF caused by incomplete redirect chain validation. Application validates initial URL against private/internal IP ranges but fails to re-validate final destination after HTTP 3xx redirects. Attacker-controlled public URLs trigger server-side fetches that follow redirects to RFC1918 addresses, cloud metadata endpoints, or localhost services, bypassing allowlist controls.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (GitHub_M) PRIMARY 8.2 HIGH

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

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

Unchanged

Confidentiality

High

Integrity

None

Availability

Low

Lifecycle Timeline

Analysis Updated

Apr 16, 2026 - 05:58 EUVD-patch-fix

executive summary

Patch available

Apr 16, 2026 - 05:29 EUVD

2.21.5

CVE Published

Apr 10, 2026 - 19:20 nvd

HIGH 8.2

DescriptionCVE.org

Postiz is an AI social media scheduling tool. Prior to 2.21.5, the /api/public/stream endpoint is vulnerable to SSRF. Although the application validates the initially supplied URL and blocks direct private/internal hosts, it does not re-validate the final destination after HTTP redirects. As a result, an attacker can supply a public HTTPS URL that passes validation and then redirects the server-side request to an internal resource.

Executive ViewAI

Why It Matters

Postiz versions before 2.21.5 contain an unauthenticated server-side request forgery vulnerability that allows attackers to access internal network resources and exfiltrate sensitive data through the /api/public/stream endpoint. This directly exposes any organization running vulnerable Postiz instances to unauthorized access of internal systems and confidential information without requiring user credentials.

Business Impact: High

Compensating Controls

Vendor-released patch: version 2.21.5. Until patching is completed: (1) Restrict network access to Postiz instances using firewall rules to limit which internal resources the application can reach; (2) Disable or restrict access to the /api/public/stream endpoint at the WAF/proxy layer if business operations permit; (3) Monitor outbound connections from Postiz servers for anomalous internal IP access attempts; (4) Implement network segmentation to isolate Postiz infrastructure from sensitive internal systems.

Threat Intelligence Overview

EPSS Score

0.0%

Top 88% exploitable

Social Media

Sightings

Data Quality

6 sources

Confidence: High

EUVD

NVD

CVE.org

EPSS

Vulnrichment CIRCL

GitHub

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity HIGH

CISA KEV No

Public POC No

EPSS 0.0%

Patch available Yes

Active threat No

Deciding rule

HIGH severity (CVSS 7.0-8.9)

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.