CVE-2026-42556: Gitroom Postiz

Critical severity, CVSS 9.0. EPSS: 0.4% chance of exploitation in the next 30 days.

Postiz is an AI social media scheduling tool. From version 2.21.6 to before version 2.21.7, any authenticated user who can create a post can store arbitrary HTML in post content by tampering their own save request and send the public preview link /p/<postId>?share=true to another user. The preview page renders that stored HTML with dangerouslySetInnerHTML on the main application origin. This issue has been patched in version 2.21.7.

Affected products

• Gitroom Postiz: version 2.21.6 only

Published 2026-05-08. Last modified 2026-07-24.