GHSA-rfr2-mq9m-x2qx datamodel-code-generator vulnerable to SSRF via --url: no host/IP validation, follows redirects

• PyPI datamodel-code-generator: >= 0.9.1, < 0.61.0 → fixed in 0.61.0

Summary `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). Details Sink: `src/datamodel_code_generator/http.py`, `get_body` (lines 31–61, at tag `0.60.1` / commit `a321547e`): ```python def get_body(url, headers=None, ignore_tls=False, query_parameters=None, timeout=DEFAULT_HTTP_TIMEOUT) -> str: httpx = _get_httpx() try: response = httpx.get( url, headers=headers, verify=not ignore_tls, follow_redirects=True, # (A) params=query_parameters, timeout=timeout, ) except Exception as e: ... if response.status_code >= 400: ... content_type = response.headers.get("content-type", "").lower() if "text/html" in content_type: raise SchemaFetchError(...) # (B) — only filter return response.text # (C) → embedded in generated.py ``` • (A) follows redirects unconditionally — a public URL → 302 → internal address chain works. • (B) the only filter is rejecting `text/html`. Non-HTML internal endpoints (JSON APIs, cloud metadata, admin services) pass through. • (C) the response body becomes the schema; its `title`, `description`, `properties`, etc. land in the generated `.py` as class attributes and `Field(description=...)` strings. `get_body` is called by `parser/base.py:1326` (`_get_text_from_url`), which is reached from CLI argument `--url `. (The `$ref` path is a separate advisory — see GHSA-D.) Only affects users who installed the `[http]` extra (`pip install 'datamodel-code-generator[http]'`). PoC A self-contained one-file PoC available here: https://gist.github.com/thegr1ffyn/18de777d6c800a3b47715425e3f3e8f5 Impact 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: 1. 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/`, and the IAM credentials end up as a docstring in `user.py`. 2. Internal port scan / disclosure. Iterating `--url http://127.0.0.1:/health` probes localhost services; non-HTML, non-error responses confirm a service and leak its body into the generated file. 3. CI poisoning. A PR adds a Makefile rule that calls `datamodel-codegen --url $(SCHEMA_URL)`; the CI runner reaches every internal service in its VPC and the response lands in PR artifacts. Suggested fix. Resolve the URL host, reject loopback / private / link-local / multicast / reserved IPs by default, disable redirects by default (`follow_redirects=False`), re-validate after each redirect if the user opts into following them, and add an `--allow-private-network` flag for opt-in legitimate use. Maintainer resolution This report was fixed together with GHSA-954p-556p-r752 by the private security PR koxudaxi/datamodel-code-generator-ghsa-rfr2-mq9m-x2qx#1, merged into the public repository as 5fdba4a09f2d7a9996a504975b7ef7d63e3715bb. Follow-up generated-file and coverage fixes were merged in koxudaxi/datamodel-code-generator#3279 and docs were synced in #3280. The patched release is 0.61.0. The patch hardens the shared HTTP fetcher used by both direct CLI `--url` fetching and remote JSON Schema/OpenAPI `$ref` resolution: • validates HTTP(S) URLs before fetching; • blocks localhost, loopback, private, link-local, reserved, and other non-public network targets by default; • disables automatic redirect following and validates each redirect target before requesting it; • adds `--allow-private-network` / `allow_private_network=True` as an explicit opt-in for trusted internal schema endpoints. Remote `$ref` fetching remains controlled by `--allow-remote-refs`; non-public/internal targets additionally require `--allow-private-network`. Submitted by: Hamza Haroon (thegr1ffyn)