NixOS's Onlyoffice is a software suite that offers online and offline tools for document editing, collaboration, and management. In versions from 22.11 to before 25.05 and versions before Unstable 25.11, a hard-coded secret was used in the NixOS module for the OnlyOffice document server to protect its file cache. An attacker with knowledge of an existing revision ID could use this secret to obtain a document. In practice, an arbitrary revision ID should be hard to obtain. The primary impact is likely the access to known documents from users with expired access. This issue was resolved in NixOS unstable version 25.11 and version 25.05.