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CVE-2026-40487

8.9 · HIGH

Postiz is an AI social media scheduling tool.

Published Apr 18, 2026CWE-79EPSS 0.26%

Overview

CVE-2026-40487 is a high-severity vulnerability. It was published on April 18, 2026 and has a CVSS 3.1 base score of 8.9 (HIGH).

This vulnerability has a CVSS 3.1 base score of 8.9, rated HIGH. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

Technical description

Postiz is an AI social media scheduling tool. Prior to version 2.21.6, a file upload validation bypass allows any authenticated user to upload arbitrary HTML, SVG, or other executable file types to the server by spoofing the `Content-Type` header. The uploaded files are then served by nginx with a Content-Type derived from their original extension (`text/html`, `image/svg+xml`), enabling Stored Cross-Site Scripting (XSS) in the context of the application's origin. This can lead to session riding, account takeover, and full compromise of other users' accounts. Version 2.21.6 contains a fix.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/gitroomhq/postiz-app/releases/tag/v2.21.6GitHubgithub.com/gitroomhq/postiz-app/security/advisories/GHSA-44wg-r34q-hvfxGitHubgithub.com/gitroomhq/postiz-app/security/advisories/GHSA-44wg-r34q-hvfx

How CyberStrike helps

Frequently asked questions

What is CVE-2026-40487?

CVE-2026-40487 is a high-severity vulnerability. It was published on April 18, 2026 and has a CVSS 3.1 base score of 8.9 (HIGH).

How severe is CVE-2026-40487?

This vulnerability has a CVSS 3.1 base score of 8.9, rated HIGH. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2026-40487?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-40487?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-40487 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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