PT-2026-65670 · Pypi · Datamodel-Code-Generator

Published

2026-07-28

·

Updated

2026-07-28

CVSS v3.1

7.8

High

VectorAV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Summary

datamodel-code-generator is vulnerable to code injection when a developer passes an --extra-template-data file whose comment value contains a literal r (carriage return). The comment variable is rendered into a Python # comment in six built-in templates with no line-terminator escaping. Python's tokenizer treats a bare CR as a physical-line terminator (see [Python language reference — Physical lines](https://docs.python.org/3/reference/lexical analysis.html#physical-lines)), so the comment ends at the r and the text after it is parsed as Python, including, when the CR is followed by suitable indentation, as a statement within the class body that follows on the next template line.

Details

The vulnerable templates each contain # {{ comment }} with no escaping:
  • src/datamodel code generator/model/template/TypeAliasAnnotation.jinja2:12 and :19
  • src/datamodel code generator/model/template/TypeAliasType.jinja2:12 and :19
  • src/datamodel code generator/model/template/TypeStatement.jinja2:12 and :19
  • src/datamodel code generator/model/template/pydantic v2/BaseModel.jinja2:4
  • src/datamodel code generator/model/template/pydantic v2/RootModel.jinja2:19
  • src/datamodel code generator/model/template/pydantic v2/RootModelTypeAlias.jinja2:13
The pydantic v2/BaseModel.jinja2:4 site is representative:
jinja2
class {{ class name }}({{ base class }}):{% if comment is defined %} # {{ comment }}{% endif %}
When the developer-supplied extras file populates comment for a model, the value reaches the template via DataModel.extra template data (set in src/datamodel code generator/model/base.py:736-742) and Jinja2 interpolates it raw. None of the templates use comment safe, escape docstring, or any other line-terminator filter.

PoC

Complete self contained POC is available at my secret gist: https://gist.github.com/thegr1ffyn/8ad6b8cb3cc2be9d3a0144aeb6896a3f

Impact

  • Who's affected: any developer or CI pipeline that runs datamodel-codegen --extra-template-data <file> where the extras file is influenced by attacker-controlled input. Realistic scenarios include:
  • Extras file generated from a third-party schema-annotation system.
  • Extras file vendored from an upstream repository.
  • Extras file produced by a script that merges multiple comment sources.
  • Build pipelines that template the extras file from environment variables, ticket descriptions, or commit metadata.
  • What it gains: arbitrary Python code execution in the importer's process at import time.
  • What it does NOT need: the schema itself can be entirely benign; only the extras file needs to contain the malicious comment.
  • What does block it: not passing --extra-template-data, or rejecting extras files whose comment values contain r, x0b, or x0c before invocation.

Resolution

The fix normalizes comment values from built-in --extra-template-data before template rendering. Inline comments now convert CRLF, bare CR, vertical tab, and form feed into LF and prefix continuation lines with # , so attacker-controlled text stays inside the generated Python comment block.

Remediation

Upgrade to datamodel-code-generator 0.60.2 or later.
This issue affects datamodel-code-generator versions >= 0.14.1, <= 0.60.1 and is fixed in 0.60.2.
Submitted by: Hamza Haroon (thegr1ffyn)

Fix

Code Injection

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Weakness Enumeration

CWE-94CWE-1336

Related Identifiers

GHSA-WJV6-JCFJ-MF9R

Affected Products

Datamodel-Code-Generator