Postiz is an AI social media scheduling tool. In versions prior to 2.21.8, the Skool integration callback signed an attacker-controlled JSON blob into a session-shape JWT using the application's JWT_SECRET, and the auth middleware trusted every claim in that JWT without re-resolving the user from the database. Any authenticated Postiz user could forge a SUPERADMIN session and impersonate arbitrary organizations.
This allowed Full Access to the following: all parts of Postiz, including users registered to the specific instance and the ability to post in the name of the victim's social media channels added to that Postiz instance. This issue has been fixed in version 2.21.8.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
Low
Basic privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
High
Complete data leak
Integrity
High
Complete data modification
Availability
High
Complete denial of service
CVSS Vector v3.1
Weakness Type (CWE)
References 4
http://github.com/gitroomhq/postiz-app/releases/tag/v2.21.8
security-advisories@github.com
https://gadvisory.org/advisories/PSA-2026-2CAQ96
security-advisories@github.com
https://github.com/gitroomhq/postiz-app/commit/23696d2973510ae1f3f48bfa41a6bfbb…
security-advisories@github.com
https://github.com/gitroomhq/postiz-app/security/advisories/GHSA-j77w-h625-56q2
security-advisories@github.com