CVE-2026-40487
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.
Attack Parameters
Technical Impact
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Recommended Solution
Immediate Action Plan
1. Inventory
Identify all affected systems in your infrastructure.
2. Assessment
Assess exposure and criticality for your organization.
3. Mitigation
Apply patches or available workarounds.
4. Verification
Test and confirm effectiveness of applied measures.