CVE-2026-40487

8.9 HIGH
Published: April 18, 2026 Modified: April 23, 2026
View on NVD

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.

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:L

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
https://github.com/gitroomhq/postiz-app/releases/tag/v2.21.6
Source: security-advisories@github.com
Product Release Notes
https://github.com/gitroomhq/postiz-app/security/advisories/GHSA-44wg-r34q-hvfx
Source: security-advisories@github.com
Exploit Vendor Advisory
https://github.com/gitroomhq/postiz-app/security/advisories/GHSA-44wg-r34q-hvfx
Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
Exploit Vendor Advisory

3 reference(s) from NVD

Quick Stats

CVSS v3 Score
8.9 / 10.0
EPSS (Exploit Probability)
0.2%
13th percentile
Exploitation Status
Not in CISA KEV

Affected Vendors

gitroom