Postiz is an AI social media scheduling tool. Prior to 2.21.8, Postiz fails to verify Nowpayments IPN callback authenticity against the payment provider shared secret and reads the target subscription identifier from the untrusted request body, allowing a low-privileged account to grant arbitrary organizations lifetime PRO subscriptions without payment. This issue is 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
None
No data leak
Integrity
High
Complete data modification
Availability
None
No disruption
CVSS Vector v3.1
Weakness Type (CWE)
References 4
https://gadvisory.org/advisories/PSA-2026-Q3TCPK
security-advisories@github.com
https://github.com/gitroomhq/postiz-app/commit/23696d2973510ae1f3f48bfa41a6bfbb…
security-advisories@github.com
https://github.com/gitroomhq/postiz-app/releases/tag/v2.21.8
security-advisories@github.com
https://github.com/gitroomhq/postiz-app/security/advisories/GHSA-j7rp-5mgj-qgg9
security-advisories@github.com