Vulnerability Analysis
Postiz Has Unrestricted File Upload via MIME Type Spoofing that Leads to Stored XSS
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.
No Active Exploit Signals
CVSS Base Score
8.9
HIGH
Exploitability:2.3
Impact Score:6.0
Temporal Score:-
EPSS:0.22%
Threat Intelligence Signals
CISA KEV
No
KEV Date Added
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Ransomware Use
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KEV Due Date
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VulnCheck In-the-Wild
No
Nuclei Template
No
EPSS Score
0.224%
EPSS Percentile
12.9th pct
GHSA ID
—
GitHub Severity
—
SSVC Exploitation
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SSVC Automatable
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Vulnerability Class
—
Identity & Timeline
| Status | - |
| Assigning Authority | - |
| CVSS Version / Source | - |
| Reserved | - |
| Published | - |
| Patch Date (date_public) | - |
| Exploit DB Date | - |
| First GitHub PoC Date | - |
| Last Updated | - |
| Time to Patch (Days to fix) | - |
| Exploit Release Gap | - |
| PoC Release Gap | - |
| Exploit DB References | None identified |
Affected Products & Versions
| Vendor | Product | Affected Versions |
|---|---|---|
| No affected products specified. | ||
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