SecuriTricks - CVE-2026-40487

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.

Product(s) Impacted

Vendor	Product	Versions
Postiz	Postiz	<2.21.6

Weaknesses

Common security weaknesses mapped to this vulnerability.

CWE-79

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

*CPE(s)

Affected systems and software identified for this CVE.

Type	Vendor	Product	Version	Update	Edition	Language	Software Edition	Target Software	Target Hardware	Other Information
a	postiz	postiz	<2.21.6	/	/	/	/	/	/	/

References

https://github.com/gitroomhq/postiz-app/releases/tag/v2.21.6

https://github.com/gitroomhq/postiz-app/security/advisories/GHSA-44wg-r34q-hvfx

CVSS Score

8.9 / 10

CVSS Data - 3.1

Attack Vector: NETWORK
Attack Complexity: LOW
Privileges Required: LOW
Scope: CHANGED
Confidentiality Impact: HIGH
Integrity Impact: HIGH
Availability Impact: LOW

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:L

View Vector String

Timeline

Published: April 18, 2026, 2:16 a.m.
Last Modified: April 18, 2026, 2:16 a.m.

Status : Received

CVE has been recently published to the CVE List and has been received by the NVD.

More info

Source

[email protected]

CVE-2026-40487