CVE-2026-100646

{
  "etk_id": "ETK-2026-262",
  "cve_id": "CVE-2026-100646",
  "display_id": "CVE-2026-100646",
  "ghsa_id": "GHSA-2w6q-wgc8-q743",
  "euvd_id": "EUVD-2026-87740",
  "status": "published",
  "anchor_state": "anchored",
  "title": "Origin validation bypass and HTML injection in SiYuan",
  "summary": "SiYuan through 3.8.3 can grant administrator access to cross-site requests that omit the Origin header and can render proxied attacker-controlled content in its local origin. A malicious website may use these conditions to execute script in the SiYuan origin, invoke administrator APIs, and obtain the persistent API token when a victim browser can access the local SiYuan service.",
  "mitigation": "Upgrade SiYuan to v3.8.4 or later. Until the upgrade is complete, restrict untrusted web content from reaching the SiYuan local HTTP service.",
  "vendor": "go",
  "product": "go:github.com/siyuan-note/siyuan",
  "affected": [
    {
      "affected_notes": [],
      "affected_ranges": [
        "<= 3.8.3"
      ],
      "ecosystem": "go",
      "fixed_versions": [
        "v3.8.4"
      ],
      "package_name": "github.com/siyuan-note/siyuan",
      "purl": "pkg:golang/github.com/siyuan-note/siyuan"
    }
  ],
  "cwes": [
    346
  ],
  "cvss_score": 9.3,
  "cvss_src": "cna_vendor",
  "cvss_vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N",
  "epss_score": 0.0019,
  "epss_percentile": 0.0853,
  "epss_asof": "2026-10-20",
  "automation": "deterministic",
  "check": true,
  "check_confidence_basis": "differential",
  "exploit": false,
  "pipeline_minutes": 35.256872933333334,
  "t0_at": "2026-09-26T13:23:17.483000+00:00",
  "signals": {
    "check": {
      "at": "2026-10-01T18:06:16.955475+00:00",
      "days": 5.1965216721643515,
      "is_lower_bound": false,
      "measured_at": "2026-09-26T13:23:17.483000+00:00",
      "url": null
    },
    "public_poc": {
      "at": "2026-09-07T17:29:33+00:00",
      "days": -18.828987071759258,
      "is_lower_bound": false,
      "measured_at": "2026-09-26T13:23:17.483000+00:00",
      "url": "https://github.com/siyuan-note/siyuan/security/advisories/GHSA-2w6q-wgc8-q743"
    },
    "trigger_signal": {
      "at": "2026-09-26T13:23:17.483000+00:00",
      "days": 0,
      "is_lower_bound": false,
      "measured_at": "2026-09-26T13:23:17.483000+00:00",
      "url": "https://github.com/siyuan-note/siyuan/security/advisories/GHSA-2w6q-wgc8-q743"
    }
  }
}