{"id":"CVE-2026-40107","aliases":["GHSA-w95v-4h65-j455","GO-2026-5702"],"url":"https://o3.security/vulnerability/CVE-2026-40107","summary":"SiYuan Affected by Zero-Click NTLM Hash Theft and Blind SSRF via Mermaid Diagram Rendering","details":"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":"2026-08-12T03:51:31.480136391Z","cvss":null,"epss":{"score":0.00306,"percentile":0.2291,"asOf":"2026-08-06"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Go","name":"github.com/siyuan-note/siyuan/kernel","fixedVersion":"0.0.0-20260407035653-2f416e5253f1"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/40xxx/CVE-2026-40107.json"},{"type":"ADVISORY","url":"https://github.com/siyuan-note/siyuan/security/advisories/GHSA-w95v-4h65-j455"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-40107"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:31.480136391Z"}}