CVE-2026-40487
HIGHPostiz Has Unrestricted File Upload via MIME Type Spoofing that Leads to Stored XSS
Title source: cnaDescription
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.
Exploits (1)
Scores
CVSS v3
8.9
EPSS
0.0002
EPSS Percentile
5.5%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:L
Details
CWE
CWE-345
CWE-434
CWE-79
Status
published
Products (2)
gitroom/postiz
< 2.21.6
gitroomhq/postiz-app
< 2.21.6
Published
Apr 18, 2026
Tracked Since
Apr 18, 2026