CVE-2026-33203: SiYuan has an Unauthenticated WebSocket DoS via Auth Keepalive Bypass

March 18, 2026 (updated March 25, 2026)

The SiYuan kernel WebSocket server accepts unauthenticated connections when a specific “auth keepalive” query parameter is present. After connection, incoming messages are parsed using unchecked type assertions on attacker-controlled JSON.

A remote attacker can send malformed messages that trigger a runtime panic, potentially crashing the kernel process and causing denial of service.

References

github.com/advisories/GHSA-3g9h-9hp4-654v
github.com/siyuan-note/siyuan
github.com/siyuan-note/siyuan/security/advisories/GHSA-3g9h-9hp4-654v
nvd.nist.gov/vuln/detail/CVE-2026-33203

Code Behaviors & Features

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