{"id":"PYSEC-2026-3564","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) -\u003e 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 \u003e= 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 \u003cURL\u003e`. (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/\u003crole\u003e`, and the IAM credentials end up as a docstring in `user.py`.\n2. **Internal port scan / disclosure.** Iterating `--url http://127.0.0.1:\u003cport\u003e/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)","aliases":["CVE-2026-54691","GHSA-rfr2-mq9m-x2qx"],"modified":"2026-08-04T14:30:15.062247391Z","published":"2026-08-04T11:34:44.095724Z","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"},{"type":"PACKAGE","url":"https://pypi.org/project/datamodel-code-generator"},{"type":"ADVISORY","url":"https://github.com/advisories/GHSA-rfr2-mq9m-x2qx"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-54691"}],"affected":[{"package":{"name":"datamodel-code-generator","ecosystem":"PyPI","purl":"pkg:pypi/datamodel-code-generator"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.9.1"},{"fixed":"0.61.0"}]}],"versions":["0.10.0","0.10.1","0.10.2","0.10.3","0.11.0","0.11.1","0.11.10","0.11.11","0.11.12","0.11.13","0.11.14","0.11.15","0.11.16","0.11.17","0.11.18","0.11.19","0.11.2","0.11.20","0.11.3","0.11.4","0.11.5","0.11.6","0.11.7","0.11.8","0.11.9","0.12.0","0.12.1","0.12.2","0.12.3","0.13.0","0.13.1","0.13.2","0.13.3","0.13.4","0.13.5","0.14.0","0.14.1","0.15.0","0.16.0","0.16.1","0.17.0","0.17.1","0.17.2","0.18.0","0.18.1","0.19.0","0.20.0","0.21.0","0.21.1","0.21.2","0.21.3","0.21.4","0.21.5","0.22.0","0.22.1","0.23.0","0.24.0","0.24.1","0.24.2","0.25.0","0.25.1","0.25.2","0.25.3","0.25.4","0.25.5","0.25.6","0.25.7","0.25.8","0.25.9","0.26.0","0.26.1","0.26.2","0.26.3","0.26.4","0.26.5","0.27.0","0.27.1","0.27.2","0.27.3","0.28.0","0.28.1","0.28.2","0.28.3","0.28.4","0.28.5","0.29.0","0.30.0","0.30.1","0.30.2","0.31.0","0.31.1","0.31.2","0.32.0","0.33.0","0.34.0","0.35.0","0.36.0","0.37.0","0.38.0","0.39.0","0.40.0","0.41.0","0.42.0","0.42.1","0.42.2","0.43.0","0.43.1","0.44.0","0.45.0","0.46.0","0.47.0","0.48.0","0.49.0","0.50.0","0.51.0","0.52.0","0.52.1","0.52.2","0.53.0","0.54.0","0.54.1","0.55.0","0.56.0","0.56.1","0.57.0","0.58.0","0.59.0","0.59.1","0.60.0","0.60.1","0.60.2","0.9.1","0.9.2","0.9.3","0.9.4"],"database_specific":{"source":"https://github.com/pypa/advisory-database/blob/main/vulns/datamodel-code-generator/PYSEC-2026-3564.yaml"}}],"schema_version":"1.8.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N"}]}