Home/CVE/Postiz is an AI social media scheduling tool. Prior to version 2.21.6, a file upload validation bypass allows any authen
CVE

CVE-2026-40487

Postiz is an AI social media scheduling tool. Prior to version 2.21.6, a file upload validation bypass allows any authen

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.

HIGH · CVSS 8.9 EPSS 0.00023
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  • Public exploit or PoC is available
  • CVSS base score ≥ 7.0
Sigma rules0 YARA rules0
⬡

Weakness Classification

CWE-345Insufficient Verification of Data Authenticity
CWE-434Unrestricted Upload of File with Dangerous Type
CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
▤

Affected Products & Versions

1
gitroom postiz< 2.21.6
⚠

Public Exploits & PoCs

1
pocgithub.com · GHSA-44wg-r34q-hvfxgithub.com
▣

Scoring & Timeline

8.9
HIGH · CVSS v3.1 · security-advisories@github.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD18 Apr 2026 · 02:16 AM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:L
SSVC triage · cisa-vulnrichment
Exploitation
poc
Automatable
no
Technical impact
total
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
🔗

References & Sources

1
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://github.com/gitroomhq/postiz-app/releases/tag/v2.21.6ProductRelease Notes
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