CVE-2026-55415

datamodel-code-generator generates Pydantic v2 models, dataclasses, TypedDict, and msgspec.Struct from OpenAPI, JSON Schema, GraphQL, Avro, Protobuf, and raw JSON, YAML, or CSV. From 0.11.6 until 0.64.0, datamodel-code-generator allows attacker-controlled x-python-import or customTypePath schema extensions to reach src/datamodel_code_generator/parser/jsonschema.py and generated import handling through Import.from_full_path and Imports.create_line in src/datamodel_code_generator/imports.py, allowing a newline to break out of an import statement and execute Python code when the generated model is imported. This issue is fixed in version 0.64.0.

datamodel-code-generator generates Pydantic v2 models, dataclasses, TypedDict, and msgspec.Struct from OpenAPI, JSON Schema, GraphQL, Avro, Protobuf, and raw JSON, YAML, or CSV. From 0.11.6 until 0.64.0, datamodel-code-generator allows attacker-controlled x-python-import or customTypePath schema extensions to reach src/datamodel_code_generator/parser/jsonschema.py and generated import handling through Import.from_full_path and Imports.create_line in src/datamodel_code_generator/imports.py, allowing a newline to break out of an import statement and execute Python code when the generated model is imported. This issue is fixed in version 0.64.0.

Summary

A malicious input schema (OpenAPI / JSON Schema) can execute arbitrary Python code on the machine that imports the generated model. The x-python-import and customTypePath schema extensions flow, unsanitized, into the import statements datamodel-code-generator emits. A newline embedded in the extension value breaks out of the from … import … line and injects an attacker-controlled statement at module scope, which runs at import time. This is an unauthenticated, schema-content–driven remote code execution against any consumer of the generated code (e.g. arbitrary file read,the PoC exfiltrates /etc/passwd). It survives the v0.61.0 security release that fixed the related x-python-type, default_factory, GraphQL-union-description, and validators sinks those fixes did not cover this sibling path.

Details

The sink is Import.from_full_path and Imports.create_line:

• src/datamodel_code_generator/imports.py:35 — from_full_path() only does class_path.split(".") and preserves every other character, including newlines:

  @classmethod
  @lru_cache
  def from_full_path(cls, class_path: str) -> Import:
      split_class_path: list[str] = class_path.split(".")
      return cls(import_=split_class_path[-1], from_=".".join(split_class_path[:-1]) or None)
  

• src/datamodel_code_generator/imports.py:64 — create_line() renders the result verbatim:

  def create_line(self, from_: str | None, imports: set[str]) -> str:
      if from_:
          return f"from {from_} import {', '.join(self._set_alias(from_, imports))}"
      return "\n".join(f"import {i}" for i in self._set_alias(from_, imports))
  

There is no check that the path segments are Python identifiers, contrast validators._validate_dotted_python_identifier_path, which the same v0.61.0 release added for the validators config, and types.is_python_type_annotation, added for x-python-type. The two extensions below were left unguarded.

Two schema-controlled, default-config entry points reach this sink:

1. x-python-import — src/datamodel_code_generator/parser/jsonschema.py:1851-1858 (get_ref_data_type):

   x_python_import = ref_schema.extras.get("x-python-import")
   if isinstance(x_python_import, dict):
       module = x_python_import.get("module")
       type_name = x_python_import.get("name")
       if module and type_name:
           full_path = f"{module}.{type_name}"
           import_ = Import.from_full_path(full_path)
           self.imports.append(import_)
   

2. customTypePath — declared at src/datamodel_code_generator/parser/jsonschema.py:438, consumed at :4118 and :4365 via get_data_type_from_full_path(custom_type_path, is_custom_type=True) → the same Import.from_full_path sink.

Mechanism. With name = "getcwd\nprint(...)", full_path = "os.getcwd\nprint(...)". from_full_path splits only on ., so (provided the injected statement contains no .) it yields from_="os" and import_="getcwd\nprint(...)". create_line then emits:

from os import getcwd
print(...)        # ← attacker statement at module scope, executes on import

The dot-split is the only constraint on the payload; it is trivially satisfied with attribute-free builtins (e.g. print(*open('/etc/passwd'), file=open('/tmp/loot','w'), sep='', end='') reads and exfiltrates a file using no .).

None of the six v0.61.0 fix commits (aec47bc4, b73abb5c, 17fc235e, 2c93c9b7, a43d0290, 5fdba4a0) touched x-python-import, customTypePath, or imports.py; imports.py was last modified ~5 months before the release. This is therefore an incomplete fix: the maintainer hardened sibling schema-controlled type/extension sinks but missed these two paths into the same import-generation code.

PoC

Self contained POC available here: https://gist.github.com/thegr1ffyn/c3abb41bb89c164daa0d5f2c60b5328b

Default invocation, no special…

datamodel-code-generator generates Pydantic v2 models, dataclasses, TypedDict, and msgspec.Struct from OpenAPI, JSON Schema, GraphQL, Avro, Protobuf, and raw JSON, YAML, or CSV. From 0.11.6 until 0.64.0, datamodel-code-generator allows attacker-controlled x-python-import or customTypePath schema extensions to reach src/datamodel_code_generator/parser/jsonschema.py and generated import handling through Import.from_full_path and Imports.create_line in src/datamodel_code_generator/imports.py, allowing a newline to break out of an import statement and execute Python code when the generated model is imported. This issue is fixed in version 0.64.0.

datamodel-code-generator generates Pydantic v2 models, dataclasses, TypedDict, and msgspec.Struct from OpenAPI, JSON Schema, GraphQL, Avro, Protobuf, and raw JSON, YAML, or CSV. From 0.11.6 until 0.64.0, datamodel-code-generator allows attacker-controlled x-python-import or customTypePath schema extensions to reach src/datamodel_code_generator/parser/jsonschema.py and generated import handling through Import.from_full_path and Imports.create_line in src/datamodel_code_generator/imports.py, allowing a newline to break out of an import statement and execute Python code when the generated model is imported. This issue is fixed in version 0.64.0.

Summary

A malicious input schema (OpenAPI / JSON Schema) can execute arbitrary Python code on the machine that imports the generated model. The x-python-import and customTypePath schema extensions flow, unsanitized, into the import statements datamodel-code-generator emits. A newline embedded in the extension value breaks out of the from … import … line and injects an attacker-controlled statement at module scope, which runs at import time. This is an unauthenticated, schema-content–driven remote code execution against any consumer of the generated code (e.g. arbitrary file read,the PoC exfiltrates /etc/passwd). It survives the v0.61.0 security release that fixed the related x-python-type, default_factory, GraphQL-union-description, and validators sinks those fixes did not cover this sibling path.

Details

The sink is Import.from_full_path and Imports.create_line:

• src/datamodel_code_generator/imports.py:35 — from_full_path() only does class_path.split(".") and preserves every other character, including newlines:

  @classmethod
  @lru_cache
  def from_full_path(cls, class_path: str) -> Import:
      split_class_path: list[str] = class_path.split(".")
      return cls(import_=split_class_path[-1], from_=".".join(split_class_path[:-1]) or None)
  

• src/datamodel_code_generator/imports.py:64 — create_line() renders the result verbatim:

  def create_line(self, from_: str | None, imports: set[str]) -> str:
      if from_:
          return f"from {from_} import {', '.join(self._set_alias(from_, imports))}"
      return "\n".join(f"import {i}" for i in self._set_alias(from_, imports))
  

There is no check that the path segments are Python identifiers, contrast validators._validate_dotted_python_identifier_path, which the same v0.61.0 release added for the validators config, and types.is_python_type_annotation, added for x-python-type. The two extensions below were left unguarded.

Two schema-controlled, default-config entry points reach this sink:

1. x-python-import — src/datamodel_code_generator/parser/jsonschema.py:1851-1858 (get_ref_data_type):

   x_python_import = ref_schema.extras.get("x-python-import")
   if isinstance(x_python_import, dict):
       module = x_python_import.get("module")
       type_name = x_python_import.get("name")
       if module and type_name:
           full_path = f"{module}.{type_name}"
           import_ = Import.from_full_path(full_path)
           self.imports.append(import_)
   

2. customTypePath — declared at src/datamodel_code_generator/parser/jsonschema.py:438, consumed at :4118 and :4365 via get_data_type_from_full_path(custom_type_path, is_custom_type=True) → the same Import.from_full_path sink.

Mechanism. With name = "getcwd\nprint(...)", full_path = "os.getcwd\nprint(...)". from_full_path splits only on ., so (provided the injected statement contains no .) it yields from_="os" and import_="getcwd\nprint(...)". create_line then emits:

from os import getcwd
print(...)        # ← attacker statement at module scope, executes on import

The dot-split is the only constraint on the payload; it is trivially satisfied with attribute-free builtins (e.g. print(*open('/etc/passwd'), file=open('/tmp/loot','w'), sep='', end='') reads and exfiltrates a file using no .).

None of the six v0.61.0 fix commits (aec47bc4, b73abb5c, 17fc235e, 2c93c9b7, a43d0290, 5fdba4a0) touched x-python-import, customTypePath, or imports.py; imports.py was last modified ~5 months before the release. This is therefore an incomplete fix: the maintainer hardened sibling schema-controlled type/extension sinks but missed these two paths into the same import-generation code.

PoC

Self contained POC available here: https://gist.github.com/thegr1ffyn/c3abb41bb89c164daa0d5f2c60b5328b

Default invocation, no special…

Summary

A malicious input schema (OpenAPI / JSON Schema) can execute arbitrary Python code on the machine that imports the generated model. The x-python-import and customTypePath schema extensions flow, unsanitized, into the import statements datamodel-code-generator emits. A newline embedded in the extension value breaks out of the from … import … line and injects an attacker-controlled statement at module scope, which runs at import time. This is an unauthenticated, schema-content–driven remote code execution against any consumer of the generated code (e.g. arbitrary file read,the PoC exfiltrates /etc/passwd). It survives the v0.61.0 security release that fixed the related x-python-type, default_factory, GraphQL-union-description, and validators sinks those fixes did not cover this sibling path.

Details

The sink is Import.from_full_path and Imports.create_line:

• src/datamodel_code_generator/imports.py:35 — from_full_path() only does class_path.split(".") and preserves every other character, including newlines:

  @classmethod
  @lru_cache
  def from_full_path(cls, class_path: str) -> Import:
      split_class_path: list[str] = class_path.split(".")
      return cls(import_=split_class_path[-1], from_=".".join(split_class_path[:-1]) or None)
  

• src/datamodel_code_generator/imports.py:64 — create_line() renders the result verbatim:

  def create_line(self, from_: str | None, imports: set[str]) -> str:
      if from_:
          return f"from {from_} import {', '.join(self._set_alias(from_, imports))}"
      return "\n".join(f"import {i}" for i in self._set_alias(from_, imports))
  

There is no check that the path segments are Python identifiers, contrast validators._validate_dotted_python_identifier_path, which the same v0.61.0 release added for the validators config, and types.is_python_type_annotation, added for x-python-type. The two extensions below were left unguarded.

Two schema-controlled, default-config entry points reach this sink:

1. x-python-import — src/datamodel_code_generator/parser/jsonschema.py:1851-1858 (get_ref_data_type):

   x_python_import = ref_schema.extras.get("x-python-import")
   if isinstance(x_python_import, dict):
       module = x_python_import.get("module")
       type_name = x_python_import.get("name")
       if module and type_name:
           full_path = f"{module}.{type_name}"
           import_ = Import.from_full_path(full_path)
           self.imports.append(import_)
   

2. customTypePath — declared at src/datamodel_code_generator/parser/jsonschema.py:438, consumed at :4118 and :4365 via get_data_type_from_full_path(custom_type_path, is_custom_type=True) → the same Import.from_full_path sink.

Mechanism. With name = "getcwd\nprint(...)", full_path = "os.getcwd\nprint(...)". from_full_path splits only on ., so (provided the injected statement contains no .) it yields from_="os" and import_="getcwd\nprint(...)". create_line then emits:

from os import getcwd
print(...)        # ← attacker statement at module scope, executes on import

The dot-split is the only constraint on the payload; it is trivially satisfied with attribute-free builtins (e.g. print(*open('/etc/passwd'), file=open('/tmp/loot','w'), sep='', end='') reads and exfiltrates a file using no .).

None of the six v0.61.0 fix commits (aec47bc4, b73abb5c, 17fc235e, 2c93c9b7, a43d0290, 5fdba4a0) touched x-python-import, customTypePath, or imports.py; imports.py was last modified ~5 months before the release. This is therefore an incomplete fix: the maintainer hardened sibling schema-controlled type/extension sinks but missed these two paths into the same import-generation code.

PoC

Self contained POC available here: https://gist.github.com/thegr1ffyn/c3abb41bb89c164daa0d5f2c60b5328b

Default invocation, no special…