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.
Exploitability
AV:NAC:LPR:LUI:RScope
S:CImpact
C:HI:HA:L8.9/CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:LInjection