SiYuan Affected by Zero-Click NTLM Hash Theft and Blind SSRF via Mermaid Diagram Rendering_CVE-2026-40107

{
    "lastseen": "",
    "description": "SiYuan is a personal knowledge management system. Prior to 3.6.4, SiYuan configures Mermaid.js with securityLevel: \"loose\" and htmlLabels: true. In this mode, <img> tags with src attributes survive Mermaid's internal DOMPurify and land in SVG <foreignObject> blocks. The SVG is injected via innerHTML with no secondary sanitization. When a victim opens a note containing a malicious Mermaid diagram, the Electron client fetches the URL. On Windows, a protocol-relative URL (//attacker.com/image.png) resolves as a UNC path (\\\\attacker.com\\image.png). Windows attempts SMB authentication automatically, sending the victim's NTLMv2 hash to the attacker. This vulnerability is fixed in 3.6.4.",
    "published": "2026-04-09T21:03:58.572Z",
    "modified": "2026-04-10T18:12:28.538Z",
    "type": "cve",
    "title": "SiYuan Affected by Zero-Click NTLM Hash Theft and Blind SSRF via Mermaid Diagram Rendering",
    "source": "GitHub_M",
    "references": "https://github.com/siyuan-note/siyuan/security/advisories/GHSA-w95v-4h65-j455",
    "id": "CVE-2026-40107",
    "bulletinFamily": "",
    "cwe": [
        "CWE-918"
    ],
    "cvelist": null,
    "sourceData": "siyuan-note siyuan < 3.6.4",
    "sourceHref": "",
    "cvss": {
        "score": 8.7,
        "severity": "HIGH",
        "vector": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:L/SI:L/SA:N",
        "version": "4.0"
    },
    "cvss2": [],
    "cvss3": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
            "baseSeverity": "",
            "attackVector": "",
            "attackComplexity": "",
            "privilegesRequired": "",
            "userInteraction": "",
            "scope": "",
            "confidentialityImpact": "",
            "integrityImpact": "",
            "availabilityImpact": ""
        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "siyuan",
    "version": "< 3.6.4",
    "vendor": "siyuan-note",
    "ai_description": "Zero-Click NTLM Hash Theft and Blind SSRF via Mermaid Diagram Rendering",
    "ai_severity": "High",
    "ai_vendor": "siyuan-note",
    "ai_product": "SiYuan",
    "ai_version": "< 3.6.4",
    "ai_score": 8.7
}