flyto-core has Unauthenticated Command Execution via HTTP MCP `execute_module`

{
  "id": "655fa8d0b4da361e41bc8b69849ce8eda6187b59b1e0de4f436eb7abffe40ebf",
  "url": "https://osv.dev/vulnerability/GHSA-h9f9-h6gm-wc85",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "flyto-core has Unauthenticated Command Execution via HTTP MCP `execute_module`",
    "summary": "## Unauthenticated Command Execution via HTTP MCP `execute_module` ### Summary The HTTP MCP endpoint (`POST /mcp`) in flyto-core accepts unauthenticated JSON-RPC `tools/call` requests and dispatches them to arbitrary registered modules, including `sandbox.execute_shell`, which passes attacker-controlled input directly to `asyncio.create_subprocess_shell`. An unauthenticated attacker can execute arbitrary OS commands as the flyto-core server process. By default the server binds to `127.0.0.1`, making this a High-severity local vulnerability (CVSS 8.4); if started with `--host 0.0.0.0`, it becomes remotely exploitable over the network. Dynamic reproduction confirmed command execution as `root` inside a Docker container without any `Authorization` header. ### Details flyto-core exposes an HTTP API via FastAPI. When the API is started (`flyto serve`), the MCP router is unconditionally mounted at `/mcp` (`src/core/api/server.py:75-78`). The route handler at `src/core/api/routes/mcp.py:65-66` declares `@router.post(\"\")` with **no** `Depends(require_auth)` dependency, unlike the analogous REST execution routes (`src/core/api/routes/modules.py:93`) which enforce both authentication and a module denylist. The complete unauthenticated data flow from source to sink: 1. **`src/core/api/server.py:75-78`** — `mcp_router` is mounted under `/mcp` unconditionally at app creation. 2. **`src/core/api/routes/mcp.py:65-66`** — `@router.post(\"\")` has no `Depends(require_auth)` guard; any HTTP clie",
    "evidence": "osv:GHSA-h9f9-h6gm-wc85",
    "products": [
      {
        "name": {
          "value": "flyto-core",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "2.26.4",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": [
          {
            "value": "2.26.2",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "2.26.3",
            "evidence": "/affected/0/versions"
          }
        ]
      }
    ],
    "severity": "high",
    "structured": {
      "id": "GHSA-h9f9-h6gm-wc85",
      "aliases": [
        "CVE-2026-55786",
        "GHSA-h9f9-h6gm-wc85",
        "PYSEC-2026-2482"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "2.26.2"
                },
                {
                  "fixed": "2.26.4"
                }
              ]
            }
          ],
          "package": {
            "name": "flyto-core",
            "purl": "pkg:pypi/flyto-core",
            "ecosystem": "PyPI"
          },
          "versions": [
            "2.26.2",
            "2.26.3"
          ],
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-h9f9-h6gm-wc85/GHSA-h9f9-h6gm-wc85.json"
          }
        }
      ],
      "modified": "2026-10-14T18:30:04.611883374Z",
      "provider": "osv",
      "references": [
        "https://github.com/flytohub/flyto-core/security/advisories/GHSA-h9f9-h6gm-wc85",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-55786",
        "https://github.com/flytohub/flyto-core/commit/db7f116b1d3c5dcf94aded00d14118f81f3e225e",
        "https://github.com/flytohub/flyto-core",
        "https://github.com/flytohub/flyto-core/releases/tag/v2.26.4",
        "https://github.com/pypa/advisory-database/tree/main/vulns/flyto-core/PYSEC-2026-2482.yaml"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-306",
          "CWE-78"
        ],
        "severity": "HIGH",
        "github_reviewed": true,
        "nvd_published_at": null,
        "github_reviewed_at": "2026-07-06T17:41:03Z"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-55786",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/database_specific/severity"
  },
  "source_id": "core-osv",
  "document_id": 317541,
  "published_at": "2026-07-06T17:41:03+00:00"
}