CVE-2026-72801

SiYuan's encrypted-notebook feature discloses its complete master-password attack material through two CheckAuth-only API endpoints, POST /api/system/getConf and POST /api/notebook/getNotebookConf (with getNotebookInfo in the same class). These endpoints are reachable with a publish RoleReader token or by the anonymous account whenever Publish.Auth.Enable is false, so an unauthenticated remote client can retrieve the global Argon2id salt and cost parameters, the AES-GCM KEKVerifier/KEKMAC offline verification material, and each notebook's wrapped data-encryption key (WrappedDEK/WrapNonce). Because the verifier is checked entirely offline, an attacker can run unlimited, GPU-parallelizable guesses against the master password with no rate limiting, lockout, or server-side logging, and on success unwrap the data key and decrypt every .sy file in the affected notebooks, reducing their security to the master password's offline-guessability. Self-hosted SiYuan deployments that publish encrypted notebooks without authentication, or that have shared a reader token, are affected, while deployments that keep the publish API authenticated and do not use notebook encryption are not materially exposed. No public proof-of-concept, CISA KEV listing, or in-the-wild exploitation is known (EPSS approximately 0.2%).

What to do: Set Publish.Auth.Enable to true (or otherwise require authentication for the publish API) so anonymous clients cannot reach these endpoints, and audit whether reader tokens have been shared or leaked. If an encrypted notebook was exposed this way, treat its master password as crackable offline and rotate it, re-encrypting the notebooks with a long, high-entropy passphrase. No fixed version is specified in the available data, so track the SiYuan project for a patched release and upgrade as soon as one is published.