SiYuan EUVD-2026-58618

Exploitation requires the SiYuan instance to be network-accessible from the attacker (AV:N) and the workspace must have at least one document assigned to a hidden visibility tier that is referenced by a row in a database (AttributeView) with at least one publicly visible entry. The attacker must supply a valid public database row identifier - obtainable by any user with read access to the public database view. The CVSS PR:N metric confirms no authentication is required. Exploitation is bounded to metadata disclosure (database name, row title, document path); document body content is not returned. Deployments with no hidden-tier documents or no public database rows gain no exploitable surface. Instances accessible only via localhost or protected by a network-layer authentication proxy are not exposed to remote anonymous exploitation.

The CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:N/UI:N) places this at the low-friction end of the exploit spectrum: no authentication, no complexity, and no prerequisites beyond a valid public database row ID. The confidentiality impact is rated Low (VC:L/SC:L), reflecting that only structural metadata - document paths, database names, row titles - is exposed rather than full document content. No CISA KEV listing and no confirmed POC exist at time of analysis, so active widespread exploitation is not established. EPSS data was not provided. Despite the moderate 6.9 score, the real-world priority for publicly hosted SiYuan deployments is elevated beyond what that score implies: an unauthenticated attacker can enumerate the existence and file paths of deliberately hidden documents with a single API call, which may reveal sensitive project names, confidential file system structure, or the presence of documents the operator intended to keep entirely invisible. Instances bound only to localhost or behind authentication proxies are not meaningfully exposed.

An attacker discovers a publicly exposed SiYuan instance and, through normal interaction with a shared database view, obtains the identifier of a visible database row. They send a single HTTP request to the getAttributeViewBacklinks endpoint with that row ID; the misconfigured authorization path returns metadata for all hidden documents that reference the row, including their file system paths and titles. No credentials, exploits, or victim interaction are required.