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SiYuan CVE-2026-73043

CRITICAL
Cross-site Scripting (XSS) (CWE-79)
2026-08-15 disclosure@vulncheck.com
9.4
CVSS 4.0 · Vendor: vulncheck
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Severity by source

Vendor (vulncheck) PRIMARY
9.4 CRITICAL
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
vuln.today AI
9.0 CRITICAL

Attacker needs template-authoring access (PR:L) and victim must open the content (UI:R); Electron Node integration breaks sandbox to the OS (S:C) with full C/I/A compromise.

3.1 AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H
4.0 AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

Primary rating from Vendor (vulncheck).

CVSS VectorVendor: vulncheck

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
P
Scope
X

Lifecycle Timeline

2
Analysis Generated
Aug 15, 2026 - 22:32 vuln.today
CVE Published
Aug 15, 2026 - 22:16 cve.org
CRITICAL 9.4

DescriptionCVE.org

SiYuan versions before v3.7.4 contain a remote code execution vulnerability in the Template calculation operator, which renders user-authored Go templates and stores output verbatim without sanitization. Attackers can inject malicious HTML and JavaScript into template calculations that execute in the desktop client renderer with Node integration enabled, allowing arbitrary code execution when the database is opened.

AnalysisAI

Remote code execution in SiYuan before v3.7.4 lets an authenticated attacker who can author Template calculation operators inject HTML and JavaScript that runs in the Electron desktop renderer with Node integration enabled, turning a stored cross-site scripting flaw into full arbitrary code execution when a victim opens the shared notebook/database. The Go template output is stored verbatim without sanitization, so payloads persist and fire on document render. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
Obtain template-authoring access in shared workspace
Delivery
Craft Go template with HTML/JS payload
Exploit
Deliver poisoned notebook/database to victim
Execution
Victim opens document in desktop client
Persist
Payload renders in Node-enabled Electron renderer
Impact
Execute arbitrary code on victim host

Vulnerability AssessmentAI

Exploitation 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. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment 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. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario 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. …
Remediation Vendor-released patch: upgrade to SiYuan v3.7.4 or later, which addresses the unsanitized Template calculation rendering (see GHSA-rwh7-gm74-67h6). … Detailed patch versions, workarounds, and compensating controls in full report.

Recommended ActionAI

Within 24 hours, identify all SiYuan deployments and users, restrict template calculation operator access to verified administrators only, and communicate the critical risk to all end users with guidance not to import templates from untrusted sources. …

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CVE-2026-73043 vulnerability details – vuln.today

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