CVE-2026-55389: datamodel-code-generator vulnerable to arbitrary local file read via JSON-Schema `$ref` (`file://` and `../` traversal), bypassing `--no-allow-remote-refs`

datamodel-code-generator resolves JSON-Schema $ref targets that point at the local filesystem without restricting them to the input/base directory and without honoring the remote-reference security control. In the default configuration, an attacker who controls an input schema (a “paste your OpenAPI/JSON-Schema” service, a CI job that generates models from a submitted spec, or any multi-tenant codegen platform) can read any file the process user can read and map the host filesystem. This works via either a file:// absolute URI or a ../-escaped relative reference, and it succeeds even when --no-allow-remote-refs is set.

This is an unauthenticated path-traversal / information-disclosure issue (CWE-22 / CWE-200) plus a bypass of a documented security control.