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CVE-2026-34449 critical CVSS 9.6

Vulnerability in github.com/siyuan-note/siyuan/kernel (CVE-2026-34449)

Summary

Vulnerability in github.com/siyuan-note/siyuan/kernel (CVE-2026-34449). Successful exploitation can lead to full system takeover. Exploitable via Origin. Mitigation: upgrade to 3.6.2 or later.

Original description

The description as published by the source.

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 una…

Source: NIST National Vulnerability Database NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-34449 has been found in github.com/siyuan-note/siyuan/kernel.
Attackers can target a specific entry point like Origin over the network to misuse the product.
Successful exploitation can lead to full system takeover. CVSS score: 9.6/10.
What to do: upgrade github.com/siyuan-note/siyuan/kernel to 3.6.2 or later.
If unsure, ask your IT team or search "github.com/siyuan-note/siyuan/kernel CVE-2026-34449" on the vendor's site.

CVE-2026-34449 (github.com/siyuan-note/siyuan/kernel) — CWE-942 / CVSS v3 9.6
Attack vector: remote (network-reachable) / unauthenticated
Attack surface: Origin / SIYUAN_ACCESS_AUTH_CODE
Patched: 3.6.2 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (CWE-942) exists in github.com/siyuan-note/siyuan/kernel. Attackers reach the vulnerable code path via Origin without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of github.com/siyuan-note/siyuan/kernel. Attack surface: Origin / SIYUAN_ACCESS_AUTH_CODE.

🔥 Severity

Severity: Critical (CVSS 9.6/10). Successful exploitation can lead to full system takeover.

🔧 How to fix

Update to 3.6.2.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'github.com/siyuan-note/siyuan/kernel' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    grep -r 'github.com/siyuan-note/siyuan/kernel' . | grep -v node_modules

    リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で github.com/siyuan-note/siyuan/kernel を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Apply patch patch 
    Upgrade github.com/siyuan-note/siyuan/kernel to 3.6.2

    ステージング環境で 3.6.2 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。

  3. 3
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

Go github.com/siyuan-note/siyuan/kernel
[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"3.6.2"}]}]

References

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