OS Command Injection in 9router (CVE-2026-59800)
Summary
OS command injection in 9router (CVE-2026-59800). Successful exploitation can lead to full system takeover. Exploitable via POST /api/tunnel/tailscale-install. Mitigation: upgrade to 0.4.44 or later.
Original description
The description as published by the source.
9Router before 0.4.44 contains an OS command injection vulnerability in the unauthenticated POST /api/tunnel/tailscale-install endpoint (this route is not covered by the dashboard middleware matcher, so no authorization check is applied). The sudoPassword field from the request body is written to the stdin of a 'sudo -S sh' child process. When sudo does not prompt for a password (the process runs as root, NOPASSWD is configured, or a recent sudo timestamp cache exists), the sudoPassword value is interpreted by sh as a shell command, allowing a remote unauthenticated attacker to execute arbitrary OS commands. Exploitation evidence was first observed by the Shadowserver Foundation on 2026-07-04 (UTC).
Source: GitHub Security Advisories (Global) 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-2026-59800 has been found in 9router.
Attackers can target a specific entry point like POST /api/tunnel/tailscale-install over the network to misuse the product.
Successful exploitation can lead to full system takeover. CVSS score: 9.8/10.
What to do: upgrade 9router to 0.4.44 or later.
If unsure, ask your IT team or search "9router CVE-2026-59800" on the vendor's site.
CVE-2026-59800 (9router) — CWE-78 / CVSS v3 9.8
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: POST /api/tunnel/tailscale-install / sudoPassword / USER / systemd
Patched: 0.4.44 — 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.
OS command injection (CWE-78) exists in 9router. Attackers reach the vulnerable code path via POST /api/tunnel/tailscale-install without authentication.
Check the vendor advisory for the affected versions of 9router. Attack surface: POST /api/tunnel/tailscale-install / sudoPassword / USER / systemd.
Severity: Critical (CVSS 9.8/10). Successful exploitation can lead to full system takeover.
Update to 0.4.44.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual POST /api/tunnel/tailscale-install requests with malformed payloads or SQL meta-characters. Run grep -r '9router' . 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
-
1Identify exposure identify
grep -r '9router' . | 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
9routerを grep し、稼働しているサービス・バージョンを把握する。 -
2Hunt for indicators of compromise detect
grep 'POST /api/tunnel/tailscale-install' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'アクセスログで
POST /api/tunnel/tailscale-installへの異常なリクエスト (不正な認証ヘッダ・SQLメタ文字)を過去 30〜90日分捜索。WAF/SIEM があれば該当パスのアラート発火履歴を確認。 -
3Apply patch patch
Upgrade 9router to 0.4.44ステージング環境で 0.4.44 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と、Step 2 で見つけた異常検知の続報チェックを含めること。
-
4Post-deployment verification verify
Replay attack against POST /api/tunnel/tailscale-install on staging to confirm patch closes the vector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 Step 2 と同じログクエリでアラート再発が無いか継続監視。
Affected packages
References
- advisory github.com
- advisory vulncheck.com
- advisory github.com
- advisory nvd.nist.gov
- package github.com
- web github.com
- web github.com