Postiz generates security-sensitive credentials using Math.random() instead of a cryptographically secure source. The same helper is used for OAuth access tokens, authorization codes, client secrets, organization API keys, and PKCE verifiers, meaning these credentials depend entirely on V8’s deterministic xorshift128+ PRNG state.

An unauthenticated OAuth dynamic client registration endpoint exposes freshly generated client credentials, giving attackers enough consecutive PRNG output to reconstruct that internal state. Once recovered, they can deterministically derive past and future values produced by the same generator, potentially compromising credentials belonging to other users and organizations.

Postiz is an AI social media scheduling tool. Versions prior to 2.21.8 contained an unauthenticated endpoint that accepted a signed token and applied subscription-enforcement side effects to the organization referenced in that token's claims, without verifying the token's intended purpose. The endpoint, /public/modify-subscription, could not change the persisted subscription tier, but it did execute enforcement-related side effects on the caller's own organization, including adjusting team-member enablement state, disabling integrations exceeding the asserted plan's limits, and resetting the scheduled-post cron when the asserted plan was the free tier. Impact is limited to the attacker's own organization and cannot be redirected at other tenants through this endpoint. This issue has been fixed in version 2.21.8.

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 JWTSECRET, 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.

Postiz is an AI social media scheduling tool. From version 2.21.6 to before version 2.21.7, any authenticated user who can create a post can store arbitrary HTML in post content by tampering their own save request and send the public preview link /p/<postId>?share=true to another user. The preview page renders that stored HTML with dangerouslySetInnerHTML on the main application origin. This issue has been patched in version 2.21.7.

Postiz is an AI social media scheduling tool. From version 2.16.6 to before version 2.21.7, all SSRF protections added in v2.21.4–v2.21.6 share a fundamental TOCTOU (Time-of-Check-Time-of-Use) vulnerability: isSafePublicHttpsUrl() resolves DNS to validate the target IP, but subsequent fetch() calls resolve DNS independently. An attacker controlling a DNS server can exploit this gap via DNS rebinding to redirect requests to internal network addresses. This issue has been patched in version 2.21.7.

Postiz is an AI social media scheduling tool. Prior to commit da44801, a "Pwn Request" vulnerability in the Build and Publish PR Docker Image workflow (.github/workflows/pr-docker-build.yml) allows any unauthenticated user to execute arbitrary code during the Docker build process and exfiltrate a highly privileged GITHUBTOKEN (write-all permissions). This can be achieved simply by opening a Pull Request from a fork with a maliciously modified Dockerfile.dev. This issue has been patched via commit da44801.

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.

Postiz is an AI social media scheduling tool. Prior to 2.21.5, the /api/public/stream endpoint is vulnerable to SSRF. Although the application validates the initially supplied URL and blocks direct private/internal hosts, it does not re-validate the final destination after HTTP redirects. As a result, an attacker can supply a public HTTPS URL that passes validation and then redirects the server-side request to an internal resource.