CVE-2026-54691: Datamodel code generator No Host/IP Validation, Follows Redirects Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-rfr2-mq9m-x2qx",
  "modified" : "2026-07-28T21:30:18Z",
  "published" : "2026-07-28T21:30:18Z",
  "aliases" : [ "CVE-2026-54691" ],
  "summary" : "datamodel-code-generator vulnerable to SSRF via --url: no host/IP validation, follows redirects",
  "details" : "### Summary\n\n`datamodel-code-generator`'s built-in HTTP fetcher (`http.get_body`) issues an `httpx.GET` against any URL passed to `--url` (or reached via a redirect chain) with **no allow-list, no deny-list, no IP/host validation, and `follow_redirects=True`**. Loopback addresses, RFC1918 ranges, link-local (`169.254.169.254` cloud metadata), unique-local IPv6 and any other network-accessible target are all reachable. The JSON/YAML response body is parsed as a schema and reflected into the generated `.py` source, exfiltrating the response to anyone with access to that file (commonly committed to a repository).\n\n### Details\n\nSink: `src/datamodel_code_generator/http.py`, `get_body` (lines 31–61, at tag `0.60.1` / commit `a321547e`):\n\n```python\ndef get_body(url, headers=None, ignore_tls=False,\n             query_parameters=None, timeout=DEFAULT_HTTP_TIMEOUT) -> str:\n    httpx = _get_httpx()\n    try:\n        response = httpx.get(\n            url,\n            headers=headers,\n            verify=not ignore_tls,\n            follow_redirects=True,          # (A)\n            params=query_parameters,\n            timeout=timeout,\n        )\n    except Exception as e:\n        ...\n    if response.status_code >= 400:\n        ...\n    content_type = response.headers.get(\"content-type\", \"\").lower()\n    if \"text/html\" in content_type:\n        raise SchemaFetchError(...)         # (B) — only filter\n    return response.text                    # (C) → embedded in generated.py\n```\n\n- (A) follows redirects unconditionally — a public URL → 302 → internal address chain works.\n- (B) the only filter is rejecting `text/html`. Non-HTML internal endpoints (JSON APIs, cloud metadata, admin services) pass through.\n- (C) the response body becomes the schema; its `title`, `description`, `properties`, etc. land in the generated `.py` as class attributes and `Field(description=...)` strings.\n\n`get_body` is called by `parser/base.py:1326` (`_get_text_from_url`), which is reached from CLI argument `--url <URL>`. (The `$ref` path is a separate advisory — see GHSA-D.)\n\nOnly affects users who installed the `[http]` extra (`pip install 'datamodel-code-generator[http]'`).\n\n### PoC\n\nA self-contained one-file PoC available here:\nhttps://gist.github.com/thegr1ffyn/18de777d6c800a3b47715425e3f3e8f5\n\n### Impact\n\n**Who is impacted.** Anyone who runs `datamodel-codegen` with a `--url` they didn't fully verify, or who runs it inside a network with reachable internal services. Realistic scenarios:\n\n1. **Trojan documentation / README.** A blog post or README example reads `datamodel-codegen --url https://schemas.example.com/user.json -o user.py`. The attacker controls `example.com`, redirects to `http://169.254.169.254/latest/meta-data/iam/security-credentials/<role>`, and the IAM credentials end up as a docstring in `user.py`.\n2. **Internal port scan / disclosure.** Iterating `--url http://127.0.0.1:<port>/health` probes localhost services; non-HTML, non-error responses confirm a service and leak its body into the generated file.\n3. **CI poisoning.** A PR adds a Makefile rule that calls `datamodel-codegen --url $(SCHEMA_URL)`; the CI runner reaches every internal service in its VPC and the response lands in PR artifacts.\n\n**Suggested fix.** Resolve the URL host, reject loopback / private / link-local / multicast / reserved IPs by default, disable redirects by default (`follow_redirects=False`), re-validate after each redirect if the user opts into following them, and add an `--allow-private-network` flag for opt-in legitimate use.\n\n### Maintainer resolution\n\nThis report was fixed together with GHSA-954p-556p-r752 by the private security PR koxudaxi/datamodel-code-generator-ghsa-rfr2-mq9m-x2qx#1, merged into the public repository as 5fdba4a09f2d7a9996a504975b7ef7d63e3715bb. Follow-up generated-file and coverage fixes were merged in koxudaxi/datamodel-code-generator#3279 and docs were synced in #3280. The patched release is 0.61.0.\n\nThe patch hardens the shared HTTP fetcher used by both direct CLI `--url` fetching and remote JSON Schema/OpenAPI `$ref` resolution:\n\n- validates HTTP(S) URLs before fetching;\n- blocks localhost, loopback, private, link-local, reserved, and other non-public network targets by default;\n- disables automatic redirect following and validates each redirect target before requesting it;\n- adds `--allow-private-network` / `allow_private_network=True` as an explicit opt-in for trusted internal schema endpoints.\n\nRemote `$ref` fetching remains controlled by `--allow-remote-refs`; non-public/internal targets additionally require `--allow-private-network`.\n\nSubmitted by: Hamza Haroon (thegr1ffyn)",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "datamodel-code-generator"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0.9.1"
      }, {
        "fixed" : "0.61.0"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 0.60.2"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/koxudaxi/datamodel-code-generator/security/advisories/GHSA-rfr2-mq9m-x2qx"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/koxudaxi/datamodel-code-generator/commit/5fdba4a09f2d7a9996a504975b7ef7d63e3715bb"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/koxudaxi/datamodel-code-generator"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/koxudaxi/datamodel-code-generator/releases/tag/0.61.0"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-918" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-28T21:30:18Z",
    "nvd_published_at" : null
  }
}