CVE-2026-40487
Postiz Has Unrestricted File Upload via MIME Type Spoofing that Leads to Stored XSS
CVSS Score
8.9
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-79 CWE-345 CWE-434 |
| Vendor | gitroomhq |
| Product | postiz-app |
| Published | Apr 18, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:L Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
Required
Scope
Changed
Confidentiality
High
Integrity
High
Availability
Low
Affected Versions
gitroomhq / postiz-app
< 2.21.6