Nginx UI: MCP configuration tools bypass restricted directive validation and allow secondary authenticated users to execute NJS in Nginx worker context

{
  "id": "3d17b423592f14c41f3a76d155eee057922b975e3bb513867d11415bfe9f3ae3",
  "url": "https://osv.dev/vulnerability/GHSA-5r62-gj48-897x",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Nginx UI: MCP configuration tools bypass restricted directive validation and allow secondary authenticated users to execute NJS in Nginx worker context",
    "summary": "## Summary The regular HTTP configuration API rejects restricted Nginx directives such as `load_module`, `js_import`, and `js_content`. However, the MCP configuration interface allows a secondary authenticated user to write and apply equivalent restricted configuration content. In the lab, this allowed the user to load `ngx_http_js_module.so`, import attacker-controlled JavaScript, reload Nginx, and execute NJS in the Nginx worker context. This is authenticated and is not OS command execution by itself. ## Affected component - `/mcp` - `/mcp_message` - MCP tool: `nginx_config_add` - Nginx configuration validation ## Impact A secondary authenticated user can bypass the restricted directive validation enforced by the HTTP API and execute attacker-controlled NJS inside the Nginx worker context. This may allow modification of Nginx runtime behavior, including responses, routing, headers, redirects, and request handling. ## Minimal PoC ### Preconditions - Attacker has a secondary authenticated Nginx UI account. - MCP is enabled. - Nginx has NJS available: ```bash find / -name \"ngx_http_js_module.so\" 2>/dev/null ``` Observed in the lab: ```text /usr/lib/nginx/modules/ngx_http_js_module.so ``` ### 1. HTTP API blocks the restricted config Request: ```http POST /api/configs Authorization: Content-Type: application/json ``` Body: ```json { \"name\": \"nginx.conf\", \"base_dir\": \"\", \"overwrite\": true, \"sync_node_ids\": [], \"content\": \"load_module modules/ngx_http_js_module.so;\\n\\nuser nginx;\\",
    "evidence": "osv:GHSA-5r62-gj48-897x",
    "products": [
      {
        "name": {
          "value": "github.com/0xJacky/Nginx-UI",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1.9.10-0.20260703131214-23d1934099b0",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "GHSA-5r62-gj48-897x",
      "aliases": [
        "CVE-2026-84319",
        "GHSA-5r62-gj48-897x",
        "GO-2026-6774"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "1.9.10-0.20260703131214-23d1934099b0"
                }
              ]
            }
          ],
          "package": {
            "name": "github.com/0xJacky/Nginx-UI",
            "purl": "pkg:golang/github.com/0xJacky/Nginx-UI",
            "ecosystem": "Go"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-5r62-gj48-897x/GHSA-5r62-gj48-897x.json"
          }
        }
      ],
      "modified": "2026-10-19T21:41:02.802986785Z",
      "provider": "osv",
      "references": [
        "https://github.com/0xJacky/nginx-ui/security/advisories/GHSA-5r62-gj48-897x",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-84319",
        "https://github.com/0xJacky/nginx-ui/commit/23d1934099b05b2a01589b48129dc3d3159d91c2",
        "https://github.com/0xJacky/nginx-ui",
        "https://github.com/0xJacky/nginx-ui/releases/tag/v2.4.1"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-693"
        ],
        "severity": "HIGH",
        "github_reviewed": true,
        "nvd_published_at": "2026-10-12T21:17:22Z",
        "github_reviewed_at": "2026-10-15T20:10:44Z"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-84319",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/database_specific/severity"
  },
  "source_id": "core-osv",
  "document_id": 376770,
  "published_at": "2026-10-15T20:10:44+00:00"
}

{
  "id": "5e4deb071843a290dc2f282f6066eb11e050f858e729a30e96a957bd71f4daa5",
  "url": "https://osv.dev/vulnerability/GO-2026-6774",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Nginx UI: MCP configuration tools bypass restricted directive validation and allow secondary authenticated users to execute NJS in Nginx worker context in github.com/0xJacky/Nginx-UI",
    "summary": "Nginx UI: MCP configuration tools bypass restricted directive validation and allow secondary authenticated users to execute NJS in Nginx worker context in github.com/0xJacky/Nginx-UI",
    "evidence": "osv:GO-2026-6774",
    "products": [
      {
        "name": {
          "value": "github.com/0xJacky/Nginx-UI",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1.9.10-0.20260703131214-23d1934099b0",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "GO-2026-6774",
      "aliases": [
        "CVE-2026-84319",
        "GHSA-5r62-gj48-897x",
        "GO-2026-6774"
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "1.9.10-0.20260703131214-23d1934099b0"
                }
              ]
            }
          ],
          "package": {
            "name": "github.com/0xJacky/Nginx-UI",
            "purl": "pkg:golang/github.com/0xJacky/Nginx-UI",
            "ecosystem": "Go"
          },
          "database_specific": {
            "source": "https://vuln.go.dev/ID/GO-2026-6774.json"
          },
          "ecosystem_specific": {}
        }
      ],
      "modified": "2026-10-19T21:31:51.315770196Z",
      "provider": "osv",
      "references": [
        "https://github.com/0xJacky/nginx-ui/security/advisories/GHSA-5r62-gj48-897x",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-84319",
        "https://github.com/0xJacky/nginx-ui/commit/23d1934099b05b2a01589b48129dc3d3159d91c2",
        "https://github.com/0xJacky/nginx-ui/releases/tag/v2.4.1"
      ],
      "provider_metadata": {
        "url": "https://pkg.go.dev/vuln/GO-2026-6774",
        "review_status": "UNREVIEWED"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-84319",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 376707,
  "published_at": "2026-10-19T21:08:35+00:00"
}