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CVE-2026-72809 high CVSS 8.0

Vulnerability in github.com/siyuan-note/siyuan/kernel (CVE-2026-72809)

Summary

Vulnerability in github.com/siyuan-note/siyuan/kernel (CVE-2026-72809). Confidential information can be exposed externally. Exploitable via CheckAuth. Mitigation: upgrade to 0.0.0-20260723031701-9c16e9851f0b or later.

Original description

The description as published by the source.

CVE: This vulnerability corresponds to CVE-2026-72809.

Summary

The kernel's CheckAuth grants RoleAdministrator to any request whose RemoteAddr is loopback (127.0.0.1), for a specific set of endpoints, and these localhost bypasses sit outside the accessAuthCode gate so they apply even when an access auth code is configured. This is demonstrated live (Part A below).

Separately, the fixed-port reverse proxy (fixedport.go) forwards requests to the kernel over loopback and injects no authentication token, and no SetTrustedProxies is configured, so gin does not derive the client address from forwarding headers. By code inspection, a request forwarded through this proxy would reach the kernel with RemoteAddr = 127.0.0.1. If the fixed-port proxy is bound to a network interface (via NetworkServe) and forwards remote requests to the kernel this way, the localhost bypass would grant a remote unauthenticated caller admin on those endpoints. This second step is established by reading the code but was not reproduced end-to-end, and I'm asking the maintainer to confirm the proxy's runtime forwarding behavior (Part B below).

Details

Localhost-trust admin bypass (proven). CheckAuth (session.go:298-321) contains localhost-only bypasses that key off RemoteAddr and grant RoleAdministrator. They sit outside the accessAuthCode gate i.e. they apply even when an access auth code is set and…

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-2026-72809 has been found in github.com/siyuan-note/siyuan/kernel.
Attackers can target a specific entry point like CheckAuth over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 8.0/10.
What to do: upgrade github.com/siyuan-note/siyuan/kernel to 0.0.0-20260723031701-9c16e9851f0b or later.
If unsure, ask your IT team or search "github.com/siyuan-note/siyuan/kernel CVE-2026-72809" on the vendor's site.

CVE-2026-72809 (github.com/siyuan-note/siyuan/kernel) — CWE-290 / CVSS v3 8.0
Attack vector: local / unauthenticated / no user interaction
Attack surface: CheckAuth / RoleAdministrator / RemoteAddr / accessAuthCode
Patched: 0.0.0-20260723031701-9c16e9851f0b — 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-290) exists in github.com/siyuan-note/siyuan/kernel. Attackers reach the vulnerable code path via CheckAuth without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of github.com/siyuan-note/siyuan/kernel. Attack surface: CheckAuth / RoleAdministrator / RemoteAddr / accessAuthCode.

🔥 Severity

Severity: High (CVSS 8.0/10). Confidential information can be exposed externally.

🔧 How to fix

Update to 0.0.0-20260723031701-9c16e9851f0b.

🛡️ 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 0.0.0-20260723031701-9c16e9851f0b

    ステージング環境で 0.0.0-20260723031701-9c16e9851f0b 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":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.0.0-20260723031701-9c16e9851f0b"}]}]

References

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