SiYuan CVE-2026-73043

Exploitation requires (1) the attacker to be able to create or edit a Template calculation operator in a SiYuan workspace - i.e., at least low-privileged authoring access (PR:L), typically via a shared/collaborative or attacker-supplied notebook; (2) the use of the desktop Electron client, whose renderer runs with Node integration enabled - this is the exact condition that upgrades stored XSS to RCE; and (3) victim interaction (UI:P) - the target must open the database/note so the unsanitized rendered output executes. Limiting factors: it is not unauthenticated (the attacker needs write/template access to the content the victim opens), it depends on the desktop client rather than a purely browser-based view, and it affects only versions before v3.7.4.

Signals are largely consistent toward high real-world severity: the CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:L/UI:P) yields 9.4 (Critical), reflecting network reach, low complexity, and high vulnerable- and subsequent-system impact via the Electron scope break. Two limiting factors temper this: PR:L means the attacker must be able to author or contribute templates (some privilege/trust in the workspace), and UI:P means a victim must open the malicious database/note for the payload to execute - so this is a shared-document or multi-user/collaboration attack, not drive-by unauthenticated RCE. No EPSS score, POC, or KEV status was provided, so widespread automated exploitation is not evidenced; treat it as a high-priority patch for any multi-user or shared-notebook SiYuan deployment while recognizing single-user local installs face lower practical exposure.

An attacker with template-authoring access crafts a Go template calculation containing a malicious HTML/JavaScript payload and shares the notebook or database with a target. When the victim opens the document in the SiYuan desktop client, the stored payload renders in the Electron renderer with Node integration and executes attacker code on the victim's host. Given AC:L the crafting is straightforward, but UI:P means the attack hinges on the victim opening the poisoned content; no public POC has been identified.