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CVE-2026-84318 high CVSS 8.8

Vulnerability in github.com/0xJacky/Nginx-UI (CVE-2026-84318)

Summary

Vulnerability in github.com/0xJacky/Nginx-UI (CVE-2026-84318). Successful exploitation can lead to full system takeover. Exploitable via POST /api/configs. Mitigation: upgrade to 1.9.10-0.20260703131214-23d1934099b0 or later.

Original description

The description as published by the source.

Summary

The MCP tool nginx_config_add writes nginx configuration files to disk and triggers an nginx reload without calling config.ValidateConfigFile. The identical flow in the REST API (POST /api/configs) does call that function and correctly rejects dangerous directives. An authenticated attacker can exploit this gap to write config files containing any blocked directive (perl, js_import, load_module, user root, etc.), bypassing nginx-ui's entire security layer. On a server with the nginx Perl, njs, or Lua module loaded, this is post-authentication Remote Code Execution.

Details

api/config/add.go (line 46) calls config.ValidateConfigFile before writing:

err = config.ValidateConfigFile(path, content)  // validates directives, checks blocklist
if err != nil {
    cosy.ErrHandler(c, err)
    return
}

mcp/config/config_add.go (line 79) omits that call entirely and writes directly:

err = os.WriteFile(path, []byte(content), 0644)  // no ValidateConfigFile, no blocklist check
...
res := nginx.Control(nginx.Reload)               // reload triggered immediately

config.ValidateConfigFile runs two checks:

  • ValidateConfigContent — rejects control characters, enforces encoding.
  • ValidateConfigDirectives — rejects a blocklist of dangerous directives: perl, perl_modules, perl_require, perl_set, js_import, js_set, js_content, load_module (restricted modules), user root, and others.

Neither check runs…

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-2026-84318 has been found in github.com/0xJacky/Nginx-UI.
Attackers can target a specific entry point like POST /api/configs over the network to misuse the product.
Successful exploitation can lead to full system takeover. CVSS score: 8.8/10.
What to do: upgrade github.com/0xJacky/Nginx-UI to 1.9.10-0.20260703131214-23d1934099b0 or later.
If unsure, ask your IT team or search "github.com/0xJacky/Nginx-UI CVE-2026-84318" on the vendor's site.

CVE-2026-84318 (github.com/0xJacky/Nginx-UI) — CWE-693 / CVSS v3 8.8
Attack vector: remote (network-reachable) / no user interaction
Attack surface: POST /api/configs / GET /mcp / POST /mcp_message / nginx_config_add
Patched: 1.9.10-0.20260703131214-23d1934099b0 — 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-693) exists in github.com/0xJacky/Nginx-UI. Attackers reach the vulnerable code path via POST /api/configs.

📍 Affected scope

Check the vendor advisory for the affected versions of github.com/0xJacky/Nginx-UI. Attack surface: POST /api/configs / GET /mcp / POST /mcp_message / nginx_config_add.

🔥 Severity

Severity: High (CVSS 8.8/10). Successful exploitation can lead to full system takeover.

🔧 How to fix

Update to 1.9.10-0.20260703131214-23d1934099b0.

🛡️ 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 POST /api/configs requests with malformed payloads or SQL meta-characters. Run grep -r 'github.com/0xJacky/Nginx-UI' . 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/0xJacky/Nginx-UI' . | 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/0xJacky/Nginx-UI 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
    Hunt for indicators of compromise detect 
    grep 'POST /api/configs' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'

    アクセスログで POST /api/configs 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。

  3. 3
    Apply patch patch 
    Upgrade github.com/0xJacky/Nginx-UI to 1.9.10-0.20260703131214-23d1934099b0

    ステージング環境で 1.9.10-0.20260703131214-23d1934099b0 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。

  4. 4
    Post-deployment verification verify 
    Replay attack against POST /api/configs 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

go github.com/0xJacky/Nginx-UI
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.9.10-0.20260703131214-23d1934099b0"}]}]

References

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