CVE-2026-40487 Details
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.
A vulnerability in Postiz, an AI social media scheduling tool, prior to version 2.21.6, allows authenticated users to bypass file upload validation and upload arbitrary HTML, SVG, or other executable file types. This is achieved by spoofing the 'Content-Type' header. The uploaded files are served by nginx with a Content-Type based on their original extension, enabling Stored Cross-Site Scripting (XSS) in the context of the application's origin. This vulnerability can lead to session riding, account takeover, and full compromise of other users' accounts.
Users are advised to upgrade to Postiz version 2.21.6 or later, where this vulnerability has been fixed.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Apr 20, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/gitroomhq/postiz-app/security/advisories/GHSA-44wg-r34q-hvfx | CISA-ADP | ExploitVendor Advisory |
| https://github.com/gitroomhq/postiz-app/releases/tag/v2.21.6 | [email protected] | ProductRelease Notes |
| https://github.com/gitroomhq/postiz-app/security/advisories/GHSA-44wg-r34q-hvfx | [email protected] | ExploitVendor Advisory |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-345 | Insufficient Verification of Data Authenticity | [email protected] |
| CWE-434 | Unrestricted Upload of File with Dangerous Type | [email protected] |
| CWE-79 | Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| gitroom postiz | < 2.21.6 |
CPE
Remediation
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Change History
5 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jun 17, 2026 | CVE Modified | [email protected] |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| Apr 23, 2026 | Initial Analysis | [email protected] |
| Apr 20, 2026 | CVE Modified | CISA-ADP |
| Apr 18, 2026 | New CVE Received | [email protected] |