CVE-2026-54621: `datamodel-code-generator` vulnerable to code injection via unescaped carriage return in GraphQL Union description

datamodel-code-generator is vulnerable to code injection when generating Python models from an attacker-controlled GraphQL schema. A description on a Union type, written in the regular-string form ("...") with a literal \r escape, is rendered into a Python # comment by a Jinja2 filter that handles only \n. Python’s tokenizer treats a bare CR as a physical-line terminator, so the comment ends at the \r and the text after it is parsed as module-level Python. The injected code executes at import time of the generated .py, in the context of any consumer that imports the model. No special CLI flags are required.

This affects versions >=0.25.0, <0.60.1 and is fixed in 0.60.1.