When a post is published, Postiz treats a media path that is not a web address as a file on the…

Why it is Yellow

• CVSS 9.6 critical

References

• https://gadvisory.org/advisories/PSA-2026-E9AHFV
• https://github.com/gitroomhq/postiz-app
• https://github.com/gitroomhq/postiz-app/commit/12db9bd2f428b628a62809669c3d76297e07750a
• https://github.com/gitroomhq/postiz-app/releases/tag/v2.25.3

Original description

When a post is published, Postiz treats a media path that is not a web address as a file on the server's disk, but it does not check that the file lies inside the upload directory. A registered user can store a crafted media path with a post, get it past the checks that normally restrict it, and have the publishing worker read an arbitrary file and send it as an attachment to a Discord server the user controls. The same unconfined reads can be reached through two further routes. One tells the caller whether a file exists and can exhaust the backend's memory, the other delivers the file the same way as the main route. Self-registration is open by default, so the attacker needs no existing account.