VULNERABILITY INTELLIGENCE

CVE-2026-40487

CVSS score8.9 HIGH
EPSS probability0.22%
CISA KEVNot currently listed
Published2026-04-18
Last modified2026-10-26
CVSS vectorCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:L

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.

Weakness classification

  • security-advisories@github.com: CWE-79

Primary references