SiYuan EUVD-2026-52279

Default-configuration exploitation requires a valid low-privilege account with at minimum RoleReader permissions on the target SiYuan instance - no administrator or elevated role is needed. When the publish authentication feature is disabled (a non-default but supported configuration), any network-accessible client can exploit the vulnerability without credentials. The attribute-view read endpoints must be reachable by the attacker, which is satisfied by any networked SiYuan deployment. Exploitation is strictly limited to reading JSON files accessible via the server's filesystem path resolution; no write access, code execution, or availability impact is possible. Instances that are not internet-exposed and that enforce publish authentication have a materially reduced attack surface, though authenticated insiders with RoleReader permissions remain a valid threat vector on all vulnerable versions.

The CVSS 4.0 score of 8.3 is driven by network accessibility (AV:N), low attack complexity (AC:L), and dual high-confidentiality impact (VC:H and SC:H), which accurately reflects the severity of cross-scope data disclosure. The PR:L metric is honest for default configurations requiring RoleReader credentials, but the description explicitly states that when publish authentication is disabled, anonymous clients can exploit the flaw - effectively making the authentication barrier PR:N in non-default but plausible deployments. This is a meaningful aggravating factor not fully captured in the static vector. No EPSS score was provided, and the vulnerability does not appear in the CISA KEV catalog, so exploitation in the wild is unconfirmed. No public POC has been identified. Real-world risk is moderated by SiYuan's self-hosted, personal-use nature: instances are less likely to be broadly internet-exposed compared to enterprise software, but teams or organizations self-hosting SiYuan with publish features enabled represent a credible threat surface. The pure-confidentiality impact (VI:N, VA:N) means attackers cannot modify or destroy data, limiting the scenario to exfiltration.

An attacker holding a RoleReader account (or operating anonymously against an instance with publish authentication disabled) sends an HTTP request to an attribute-view read endpoint with an avID value such as ../../../../workspace/storage/other-scope/sensitive.json. SiYuan resolves the traversal without validation and returns the raw JSON contents, exposing database records from other scopes. Because no user interaction or elevated privilege is needed, the attack can be scripted to enumerate and bulk-exfiltrate multiple data files.