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CVE-2026-34605

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

8.6 HighFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
Active

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
Low

Exploit likelihood

0.47%Up 0.5 points since Apr 1, 2026
90%50%10%1%

What each source reports

CVE List Score used 8.6

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

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.

Record
CVE-2026-34605
CVSS 4.0
8.6 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N
Weakness
CWE-79
Updated
2026-11-02
EUVDEUVD-2026-17687 8.6

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.

Record
EUVD-2026-17687
CVSS 4.0
8.6 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-73g7-86qr-jrg3 8.6

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

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.

Record
GHSA-73g7-86qr-jrg3
CVSS 4.0
8.6 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N
CVSS 3.1
6.1 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Weakness
CWE-79
Updated
2026-11-02
NVD 8.6

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.

Record
CVE-2026-34605
CVSS 4.0
8.6 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1
6.1 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Weakness
CWE-79
Updated
2026-11-02
OSV 8.6

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

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.

Record
CVE-2026-34605
CVSS 4.0
8.6 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N
Weakness
CWE-79
Updated
2026-11-02
OSVGHSA-73g7-86qr-jrg3 8.6

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

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.

Record
GHSA-73g7-86qr-jrg3
CVSS 4.0
8.6 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N
CVSS 3.1
6.1 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Weakness
CWE-79
Updated
2026-11-02
OSVGO-2026-5201 No score

SiYuan vulnerable to reflected XSS via SVG namespace prefix bypass in SanitizeSVG (getDynamicIcon, unauthenticated) in github.com/siyuan-note/siyuan/kernel

SiYuan vulnerable to reflected XSS via SVG namespace prefix bypass in SanitizeSVG (getDynamicIcon, unauthenticated) in github.com/siyuan-note/siyuan/kernel

Record
GO-2026-5201
Updated
2026-11-02
OSVopenSUSE-SU-2026:21483-1 No score

Security update for govulncheck-vulndb

This update for govulncheck-vulndb fixes the following issues:

  • Update to version 0.0.20260723T184607 2026-07-23T18:46:07Z (jsc#PED-11136).

Go CVE Numbering Authority IDs added or updated with aliases:

  • GO-2026-4730 CVE-2026-33022 GHSA-cv4x-93xx-wgfj
  • GO-2026-4761 CVE-2026-33211 GHSA-j5q5-j9gm-2w5c
  • GO-2026-5102 CVE-2026-45021 GHSA-3vcp-chfh-f6r2
  • GO-2026-5272 CVE-2026-40938 GHSA-94jr-7pqp-xhcq
  • GO-2026-5486 CVE-2026-40924 GHSA-m2cx-gpqf-qf74
  • GO-2026-5542 CVE-2026-40090 GHSA-pj97-4p9w-gx3q
  • GO-2026-5630 CVE-2026-25542 GHSA-rmx9-2pp3-xhcr
  • GO-2026-5643 CVE-2026-40923 GHSA-rx35-6rhx-7858
  • GO-2026-5675 CVE-2026-41492 GHSA-vvf7-6rmr-m29q
  • GO-2026-5711 CVE-2026-40161 GHSA-wjxp-xrpv-xpff
  • GO-2026-5746 CVE-2026-41567 GHSA-x86f-5xw2-fm2r
  • GO-2026-5749 CVE-2026-41328 GHSA-x92x-px7w-4gx4
  • GO-2026-5837 CVE-2026-44840 GHSA-q2m9-6jp9-c6mc
  • GO-2026-5929 CVE-2026-44342 GHSA-26v7-h57m-gh9m
  • GO-2026-5930 CVE-2026-33655 GHSA-6qcr-qxgr-m7fv
  • GO-2026-5933 GHSA-3g4q-2f67-2gvh
  • GO-2026-5934 GHSA-59qp-cfj3-rp64
  • GO-2026-5935 GHSA-7856-g3gv-9wq8
  • GO-2026-5936 CVE-2026-53552 GHSA-26rh-24rg-j3vv
  • GO-2026-5937 CVE-2026-53508 GHSA-2jcc-mxv7-p3f9
  • GO-2026-5938 CVE-2026-53553 GHSA-4g5x-hcwm-82jw
  • GO-2026-5939 CVE-2026-10517 GHSA-698x-9w2p-7vvp
  • GO-2026-5940 CVE-2026-53572 GHSA-6w3m-4hhp-775q
  • GO-2026-5941 CVE-2026-53487 GHSA-gvhc-wv3v-7pf8
  • GO-2026-5942 CVE-2026-46600
  • GO-2026-5944 CVE-2026-50197 GHSA-659f-rgp5-w4wf
  • GO-2026-5945 CVE-2026-6815 GHSA-rmxx-v9rj-vpvg
  • GO-2026-5946 CVE-2026-52831 GHSA-v5px-423j-pf7p
  • GO-2026-5947 CVE-2026-53649 GHSA-xqhv-chqm-fhcc
  • GO-2026-5948 CVE-2026-50554 GHSA-588f-fvcv-xhvf
  • GO-2026-5949 CVE-2026-50553 GHSA-rqrh-8wpv-x7hh
  • GO-2026-5950 CVE-2026-53602 GHSA-339v-266x-79xr
  • GO-2026-5951 CVE-2026-10219 GHSA-6jm8-4fhr-5w64
  • GO-2026-5952 CVE-2026-49834 GHSA-9vcr-p3rj-q5q6
  • GO-2026-5953 CVE-2026-9094 GHSA-c9w5-qp6m-m395
  • GO-2026-5956 CVE-2026-55252 GHSA-h5g6-xmh4-hc37
  • GO-2026-5957 CVE-2026-54158 GHSA-5xfx-xj4h-5p7r
  • GO-2026-5958 CVE-2026-54068 GHSA-gcm7-57gf-953c
  • GO-2026-5959 CVE-2026-54072 GHSA-h29v-hj44-q8cv
  • GO-2026-5961 CVE-2026-54069 GHSA-hvr9-72v2-fff3
  • GO-2026-5962 CVE-2026-54088 GHSA-m93h-4hw7-5qcm
  • GO-2026-5963 CVE-2026-54067 GHSA-mvjr-vv3c-w4qv
  • GO-2026-5964 CVE-2026-54066 GHSA-p4m3-mgmm-c664
  • GO-2026-5965 CVE-2026-54070 GHSA-w7cg-whh7-xp28
  • GO-2026-5966 CVE-2026-54089 GHSA-xqp3-jq6g-x3qm
  • GO-2026-5967 CVE-2026-50551 GHSA-56mp-4f3v-fgj2
  • GO-2026-5968 CVE-2026-54174 GHSA-fpg8-7664-jc5q
  • GO-2026-5969 GHSA-g936-7jqj-mwv8
  • GO-2026-5970 CVE-2026-56852
  • GO-2026-5973 CVE-2026-54250 GHSA-jxr7-mqhw-9p98
  • GO-2026-5974 CVE-2026-44300 GHSA-wmj8-9953-vff5
  • GO-2026-5975 CVE-2026-50018 GHSA-42j2-w334-qxw7
  • GO-2026-5976 CVE-2026-50141 GHSA-g7mm-9vx7-jm7h
  • GO-2026-5977 CVE-2026-50013 GHSA-qrh4-p6v4-mrfg
  • GO-2026-5978 CVE-2026-50125 GHSA-qw5r-ppcg-f8rj
  • GO-2026-5979 CVE-2026-50006 GHSA-xrcf-6jh3-ggvx
  • GO-2026-5980 CVE-2026-50158 GHSA-2c7f-fxww-6w6c
  • GO-2026-5981 GHSA-mqxv-9rm6-w8qc
  • GO-2026-5982 GHSA-pqg7-v6wh-3pfp
  • GO-2026-5984 CVE-2026-53604 GHSA-2p2f-px33-4vv5
  • GO-2026-5985 GHSA-7rx3-5wx3-5v76
  • GO-2026-5986 CVE-2026-61699 GHSA-cm26-5974-52h8
  • GO-2026-5987 CVE-2026-55513 GHSA-g4x6-jcvr-9m3g
  • GO-2026-5988 CVE-2026-54628 GHSA-hwrq-8wxh-q4xv
  • GO-2026-5989 CVE-2026-55512 GHSA-m3cx-mwpg-32jg
  • GO-2026-5990 CVE-2026-54629 GHSA-mf78-3rpf-r784
  • GO-2026-5991 CVE-2026-53603 GHSA-q4vm-pq3q-8wgq
  • GO-2026-5992 CVE-2026-61549 GHSA-qf34-295c-26v8
  • GO-2026-5996 CVE-2026-54450 GHSA-pph6-vfjv-vpjw
  • GO-2026-5997 CVE-2026-54452 GHSA-xgch-x3mx-cm3c
  • GO-2026-5998 CVE-2026-54495 GHSA-398h-7f66-3h4p
  • GO-2026-5999 CVE-2026-10814 GHSA-jh6h-v6mp-h22v
  • GO-2026-6002 CVE-2026-58196 GHSA-pr64-jmmf-jp54
  • GO-2026-6003 CVE-2026-53714 GHSA-22xc-xg2r-9j7v
  • GO-2026-6004 CVE-2026-52833 GHSA-3v79-m2cg-89ww
  • GO-2026-6005 CVE-2026-53715 GHSA-8fv2-88gg-hm7q
  • GO-2026-6006 CVE-2026-53716 GHSA-cxpq-8v7q-cg56 *…
Record
openSUSE-SU-2026:21483-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
github.com/siyuan-note/siyuan/kernel
Go
 before 0.0.0-20260330031106-f09953afc57a
0.0.0-20260330031106-f09953afc57a
govulncheck-vulndb
openSUSE:Leap 16.0
From an advisory covering 1734 CVEs
 before 0.0.20260723T184607-160000.1.1
0.0.20260723T184607-160000.1.1

Public exploits

Links only. Every CVE stores no exploit code.

Public exploits
SourceLinkDate
NucleiSiYuan Note - Cross-Site Scripting

History

History
RecordedChangedSources
affected, facts
first indexedCVE List, EUVD, GitHub Advisories, Nuclei, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-34605 is a high vulnerability (CVSS 8.6) in B3log Siyuan, published March 31, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.47%, the 40th percentile. Fixed in github.com/siyuan-note/siyuan/kernel 0.0.0-20260330031106-f09953afc57a.

References

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