Vulnerability-Lookup

CVE-2026-34605 (GCVE-0-2026-34605)

Vulnerability from cvelistv5 – Published: 2026-03-31 21:50 – Updated: 2026-04-01 18:57

Title

SiYuan: Reflected XSS via SVG namespace prefix bypass in SanitizeSVG ( getDynamicIcon, unauthenticated )

Summary

SiYuan is a personal knowledge management system. From version 3.6.0 to before version 3.6.2, the SanitizeSVG function introduced in version 3.6.0 to fix XSS in the unauthenticated /api/icon/getDynamicIcon endpoint can be bypassed by using namespace-prefixed element names such as <x:script xmlns:x="http://www.w3.org/2000/svg">. The Go HTML5 parser records the element's tag as "x:script" rather than "script", so the tag check passes it through. The SVG is served with Content-Type: image/svg+xml and no Content Security Policy; when a browser opens the response directly, its XML parser resolves the prefix to the SVG namespace and executes the embedded script. This issue has been patched in version 3.6.2.

Severity ?

8.6 (High)


                        
                          CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N

CWE

CWE-79 - Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Assigner

GitHub_M

References

URL

Tags

	https://github.com/siyuan-note/siyuan/security/ad…	x_refsource_CONFIRM
	https://github.com/siyuan-note/siyuan/issues/17246	x_refsource_MISC
	https://github.com/siyuan-note/siyuan/releases/ta…	x_refsource_MISC

Impacted products

	Vendor	Product	Version
	siyuan-note	siyuan	Affected: >= 3.6.0, < 3.6.2

Show details on NVD website

JSON

To clipboard

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                "id": "CVE-2026-34605",
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                "role": "CISA Coordinator",
                "timestamp": "2026-04-01T18:57:28.582022Z",
                "version": "2.0.3"
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          "shortName": "CISA-ADP"
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        "discovery": "UNKNOWN"
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FKIE_CVE-2026-34605

Vulnerability from fkie_nvd - Published: 2026-03-31 22:16 - Updated: 2026-04-03 16:01

Severity ?

6.1 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Summary

References

URL	Tags
security-advisories@github.com	https://github.com/siyuan-note/siyuan/issues/17246	Issue Tracking
security-advisories@github.com	https://github.com/siyuan-note/siyuan/releases/tag/v3.6.2	Release Notes
security-advisories@github.com	https://github.com/siyuan-note/siyuan/security/advisories/GHSA-73g7-86qr-jrg3	Exploit, Vendor Advisory

Impacted products

	Vendor	Product	Version
	b3log	siyuan	*

JSON

To clipboard

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      "nodes": [
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          "cpeMatch": [
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              "criteria": "cpe:2.3:a:b3log:siyuan:*:*:*:*:*:*:*:*",
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              "vulnerable": true
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      "lang": "en",
      "value": "SiYuan is a personal knowledge management system. From version 3.6.0 to before version 3.6.2, the SanitizeSVG function introduced in version 3.6.0 to fix XSS in the unauthenticated /api/icon/getDynamicIcon endpoint can be bypassed by using namespace-prefixed element names such as \u003cx:script xmlns:x=\"http://www.w3.org/2000/svg\"\u003e. The Go HTML5 parser records the element\u0027s tag as \"x:script\" rather than \"script\", so the tag check passes it through. The SVG is served with Content-Type: image/svg+xml and no Content Security Policy; when a browser opens the response directly, its XML parser resolves the prefix to the SVG namespace and executes the embedded script. This issue has been patched in version 3.6.2."
    },
    {
      "lang": "es",
      "value": "SiYuan es un sistema de gesti\u00f3n de conocimiento personal. Desde la versi\u00f3n 3.6.0 hasta antes de la versi\u00f3n 3.6.2, la funci\u00f3n SanitizeSVG introducida en la versi\u00f3n 3.6.0 para corregir XSS en el endpoint no autenticado /API/icon/getDynamicIcon puede ser eludida mediante el uso de nombres de elementos con prefijo de espacio de nombres como . El analizador HTML5 de Go registra la etiqueta del elemento como \u0027x:script\u0027 en lugar de \u0027script\u0027, por lo que la verificaci\u00f3n de la etiqueta lo permite pasar. El SVG se sirve con Content-Type: image/svg+xml y sin Pol\u00edtica de Seguridad de Contenido; cuando un navegador abre la respuesta directamente, su analizador XML resuelve el prefijo al espacio de nombres SVG y ejecuta el script incrustado. Este problema ha sido parcheado en la versi\u00f3n 3.6.2."
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  "id": "CVE-2026-34605",
  "lastModified": "2026-04-03T16:01:29.827",
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          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
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  ]
}

GHSA-73G7-86QR-JRG3

Vulnerability from github – Published: 2026-04-01 00:30 – Updated: 2026-04-01 00:30

Summary

SiYuan vulnerable to reflected XSS via SVG namespace prefix bypass in SanitizeSVG (getDynamicIcon, unauthenticated)

Details

Summary

The SanitizeSVG function introduced in v3.6.0 to fix XSS in the unauthenticated /api/icon/getDynamicIcon endpoint can be bypassed by using namespace-prefixed element names such as <x:script xmlns:x="http://www.w3.org/2000/svg">. The Go HTML5 parser records the element's tag as "x:script" rather than "script", so the tag check passes it through. The SVG is served with Content-Type: image/svg+xml and no Content Security Policy; when a browser opens the response directly, its XML parser resolves the prefix to the SVG namespace and executes the embedded script.

Details

The getDynamicIcon route is registered without authentication:

// kernel/server/serve.go
ginServer.Handle("GET", "/api/icon/getDynamicIcon", getDynamicIcon)

For type 8, the content query parameter is inserted directly into an SVG <text> element using fmt.Sprintf with no HTML encoding:

// kernel/api/icon.go:579-584
return fmt.Sprintf(`
    <svg id="dynamic_icon_type8" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512">
        <path d="..."/>
        <text x="50%%" y="55%%" ...>%s</text>
    </svg>`, ..., content)

SanitizeSVG then parses the SVG with github.com/88250/lute/html and removes elements whose lowercased tag name matches a fixed list:

// kernel/util/misc.go:249-252
tag := strings.ToLower(c.Data)
if tag == "script" || tag == "iframe" || tag == "object" || tag == "embed" ||
    tag == "foreignobject" || "animate" == tag || ... {
    n.RemoveChild(c)

The lute HTML parser stores the full qualified name including any namespace prefix in Node.Data. A payload like <x:script xmlns:x="http://www.w3.org/2000/svg"> gets Data = "x:script". The check tag == "script" is false, so the element is not removed and survives in the rendered output.

Confirmed with the same library version used by SiYuan:

html.Parse input:  <x:script xmlns:x="http://www.w3.org/2000/svg">alert(1)</x:script>
Node.Data result:  "x:script"   (not "script")
Removed by check:  false
Rendered output:   <x:script xmlns:x="http://www.w3.org/2000/svg">alert(1)</x:script>

The same bypass works for every element on the blocklist: x:iframe, x:object, x:foreignObject, etc.

The fix is to strip the namespace prefix before comparing:

localName := tag
if i := strings.LastIndex(tag, ":"); i >= 0 {
    localName = tag[i+1:]
}
if localName == "script" || localName == "iframe" || ...

PoC

GET /api/icon/getDynamicIcon?type=8&color=red&content=%3C%2Ftext%3E%3Cx%3Ascript%20xmlns%3Ax%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%3Ealert%28document.domain%29%3C%2Fx%3Ascript%3E%3Ctext%3E HTTP/1.1
Host: 127.0.0.1:6806

Decoded content value:

</text><x:script xmlns:x="http://www.w3.org/2000/svg">alert(document.domain)</x:script><text>

The response is a valid SVG with the script element intact. Opening the URL directly in a browser triggers the alert, confirming script execution at the SiYuan server origin.

Impact

Any user whose SiYuan instance is reachable over a local network is exposed. An attacker on the same network can craft the URL and share it. When the victim opens it in a browser, JavaScript executes at the http://<siyuan-host>:6806 origin. Because SiYuan sets Access-Control-Allow-Origin: * and the script runs same-origin, it can call any API endpoint using the victim's existing session cookies, including endpoints to read all notes, export data, or modify settings. No authentication or prior access is needed to construct the payload.

Severity ?

8.6 (High)


                  
                    CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N

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{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/siyuan-note/siyuan/kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.0.0-20260330031106-f09953afc57a"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-34605"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-79"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-01T00:30:01Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "### Summary\n\nThe `SanitizeSVG` function introduced in v3.6.0 to fix XSS in the unauthenticated `/api/icon/getDynamicIcon` endpoint can be bypassed by using namespace-prefixed element names such as `\u003cx:script xmlns:x=\"http://www.w3.org/2000/svg\"\u003e`. The Go HTML5 parser records the element\u0027s tag as `\"x:script\"` rather than `\"script\"`, so the tag check passes it through. The SVG is served with `Content-Type: image/svg+xml` and no Content Security Policy; when a browser opens the response directly, its XML parser resolves the prefix to the SVG namespace and executes the embedded script.\n\n### Details\n\nThe `getDynamicIcon` route is registered without authentication:\n\n```go\n// kernel/server/serve.go\nginServer.Handle(\"GET\", \"/api/icon/getDynamicIcon\", getDynamicIcon)\n```\n\nFor type 8, the `content` query parameter is inserted directly into an SVG `\u003ctext\u003e` element using `fmt.Sprintf` with no HTML encoding:\n\n```go\n// kernel/api/icon.go:579-584\nreturn fmt.Sprintf(`\n    \u003csvg id=\"dynamic_icon_type8\" xmlns=\"http://www.w3.org/2000/svg\" viewBox=\"0 0 512 512\"\u003e\n        \u003cpath d=\"...\"/\u003e\n        \u003ctext x=\"50%%\" y=\"55%%\" ...\u003e%s\u003c/text\u003e\n    \u003c/svg\u003e`, ..., content)\n```\n\n`SanitizeSVG` then parses the SVG with `github.com/88250/lute/html` and removes elements whose lowercased tag name matches a fixed list:\n\n```go\n// kernel/util/misc.go:249-252\ntag := strings.ToLower(c.Data)\nif tag == \"script\" || tag == \"iframe\" || tag == \"object\" || tag == \"embed\" ||\n    tag == \"foreignobject\" || \"animate\" == tag || ... {\n    n.RemoveChild(c)\n```\n\nThe lute HTML parser stores the full qualified name including any namespace prefix in `Node.Data`. A payload like `\u003cx:script xmlns:x=\"http://www.w3.org/2000/svg\"\u003e` gets `Data = \"x:script\"`. The check `tag == \"script\"` is false, so the element is not removed and survives in the rendered output.\n\nConfirmed with the same library version used by SiYuan:\n\n```\nhtml.Parse input:  \u003cx:script xmlns:x=\"http://www.w3.org/2000/svg\"\u003ealert(1)\u003c/x:script\u003e\nNode.Data result:  \"x:script\"   (not \"script\")\nRemoved by check:  false\nRendered output:   \u003cx:script xmlns:x=\"http://www.w3.org/2000/svg\"\u003ealert(1)\u003c/x:script\u003e\n```\n\nThe same bypass works for every element on the blocklist: `x:iframe`, `x:object`, `x:foreignObject`, etc.\n\nThe fix is to strip the namespace prefix before comparing:\n\n```go\nlocalName := tag\nif i := strings.LastIndex(tag, \":\"); i \u003e= 0 {\n    localName = tag[i+1:]\n}\nif localName == \"script\" || localName == \"iframe\" || ...\n```\n\n### PoC\n\n```\nGET /api/icon/getDynamicIcon?type=8\u0026color=red\u0026content=%3C%2Ftext%3E%3Cx%3Ascript%20xmlns%3Ax%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%3Ealert%28document.domain%29%3C%2Fx%3Ascript%3E%3Ctext%3E HTTP/1.1\nHost: 127.0.0.1:6806\n```\n\nDecoded `content` value:\n```\n\u003c/text\u003e\u003cx:script xmlns:x=\"http://www.w3.org/2000/svg\"\u003ealert(document.domain)\u003c/x:script\u003e\u003ctext\u003e\n```\n\nThe response is a valid SVG with the script element intact. Opening the URL directly in a browser triggers the alert, confirming script execution at the SiYuan server origin.\n\n### Impact\n\nAny user whose SiYuan instance is reachable over a local network is exposed. An attacker on the same network can craft the URL and share it. When the victim opens it in a browser, JavaScript executes at the `http://\u003csiyuan-host\u003e:6806` origin. Because SiYuan sets `Access-Control-Allow-Origin: *` and the script runs same-origin, it can call any API endpoint using the victim\u0027s existing session cookies, including endpoints to read all notes, export data, or modify settings. No authentication or prior access is needed to construct the payload.",
  "id": "GHSA-73g7-86qr-jrg3",
  "modified": "2026-04-01T00:30:01Z",
  "published": "2026-04-01T00:30:01Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/siyuan-note/siyuan/security/advisories/GHSA-73g7-86qr-jrg3"
    },
    {
      "type": "WEB",
      "url": "https://github.com/siyuan-note/siyuan/issues/17246"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/siyuan-note/siyuan"
    },
    {
      "type": "WEB",
      "url": "https://github.com/siyuan-note/siyuan/releases/tag/v3.6.2"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "SiYuan vulnerable to reflected XSS via SVG namespace prefix bypass in SanitizeSVG (getDynamicIcon, unauthenticated)"
}

Sightings

Author	Source	Type	Date

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

CVE-2026-34605 (GCVE-0-2026-34605)

FKIE_CVE-2026-34605

GHSA-73G7-86QR-JRG3

Summary

Details

PoC

Impact

Tags

Sightings

Nomenclature