CVE-2026-29183: SiYuan Cross-Site Scripting Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-6865-qjcf-286f",
  "modified" : "2026-03-06T21:58:04Z",
  "published" : "2026-03-04T21:45:10Z",
  "aliases" : [ "CVE-2026-29183" ],
  "summary" : "SiYuan: Unauthenticated Reflected XSS via SVG Injection in /api/icon/getDynamicIcon Endpoint",
  "details" : "### Summary\nAn unauthenticated reflected XSS vulnerability exists in the dynamic icon API endpoint:\n\n- `GET /api/icon/getDynamicIcon`\n\nWhen `type=8`, attacker-controlled `content` is embedded into SVG output without escaping. Because the endpoint is unauthenticated and returns `image/svg+xml`, a crafted URL can inject executable SVG/HTML event handlers (for example `onerror`) and run JavaScript in the SiYuan web origin.\n\nThis can be chained to perform authenticated API actions and exfiltrate sensitive data when a logged-in user opens the malicious link.\n\n### Details\nThe issue is caused by unsafe output construction and incomplete sanitization:\n\n1. **Endpoint is exposed without auth middleware**\n   - Source: https://github.com/siyuan-note/siyuan/blob/master/kernel/api/router.go#L27-L37\n   - `GET /api/icon/getDynamicIcon` is registered in the unauthenticated section.\n\n2. **User input is inserted into SVG via string formatting**\n   - Source: https://github.com/siyuan-note/siyuan/blob/master/kernel/api/icon.go#L115-L175\n   - Source: https://github.com/siyuan-note/siyuan/blob/master/kernel/api/icon.go#L537-L585\n   - In `generateTypeEightSVG`, `%s` directly injects `content` into `<text>...</text>` without XML/HTML escaping.\n\n3. **Sanitizer only removes `<script>` tags**\n   - Source: https://github.com/siyuan-note/siyuan/blob/master/kernel/util/misc.go#L235-L281\n   - `RemoveScriptsInSVG` removes `<script>` nodes, but does not remove dangerous attributes (`onerror`, `onload`, etc.) or unsafe elements.\n\nAs a result, payloads such as `</text><image ... onerror=...><text>` survive and execute.\n\n### PoC\n\n#### Minimal browser execution PoC\nOpen this URL in a browser:\n\n```http\nGET /api/icon/getDynamicIcon?type=8&content=%3C%2Ftext%3E%3Cimage%20href%3Dx%20onerror%3Dalert(document.domain)%3E%3C%2Fimage%3E%3Ctext%3E\n```\n\nExample full URL:\n\n```text\nhttp://127.0.0.1:6806/api/icon/getDynamicIcon?type=8&content=%3C%2Ftext%3E%3Cimage%20href%3Dx%20onerror%3Dalert(document.domain)%3E%3C%2Fimage%3E%3Ctext%3E\n```\n\nExpected result:\n\n- JavaScript executes (`alert(document.domain)`), confirming reflected XSS.\n\n#### Authenticated impact demonstration\nIf a victim is authenticated in the same browser session, JavaScript running in origin can call privileged APIs and exfiltrate returned data.\n\n### Impact\nThis is a reflected XSS in an unauthenticated endpoint, with realistic account/data compromise impact:\n\n- Arbitrary JavaScript execution in SiYuan web origin.\n- Authenticated action abuse via same-origin API calls.\n- Sensitive data exposure (notes/config/API responses) from victim context.\n- Potential chained server-impact actions depending on victim privileges and deployment mode.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/siyuan-note/siyuan/kernel"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.0.0-20260304034809-d68bd5a79391"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/siyuan-note/siyuan/security/advisories/GHSA-6865-qjcf-286f"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-29183"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/siyuan-note/siyuan/commit/d68bd5a79391742b3cb2e14d892bdd9997064927"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/siyuan-note/siyuan"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-04T21:45:10Z",
    "nvd_published_at" : "2026-03-06T08:16:27Z"
  }
}