Additional properties policy

p1c2u · p1c2u · commit 157745efb748 · 2026-03-04T21:23:51.000Z
diff --git a/docs/configuration.md b/docs/configuration.md
@@ -136,7 +136,7 @@ result = openapi.unmarshal_response(request, response)
 
 By default, OpenAPI follows JSON Schema behavior: when an object schema omits `additionalProperties`, extra keys are allowed.
 
-If you want stricter behavior, enable `strict_additional_properties`. In this mode, omitted `additionalProperties` is treated as `false`.
+If you want stricter behavior, change `additional_properties_default_policy` to `forbid`. In this mode, omitted `additionalProperties` is treated as `false`.
 
 This mode is particularly useful for:
 - **Preventing data leaks**: Ensuring your API doesn't accidentally expose internal or sensitive fields in responses that aren't explicitly documented.
@@ -148,7 +148,7 @@ from openapi_core import Config
 from openapi_core import OpenAPI
 
 config = Config(
-    strict_additional_properties=True,
+    additional_properties_default_policy="forbid",
 )
 openapi = OpenAPI.from_file_path('openapi.json', config=config)
 ```
diff --git a/openapi_core/app.py b/openapi_core/app.py
@@ -427,7 +427,7 @@ def request_validator(self) -> RequestValidator:
             spec_validator_cls=self.config.spec_validator_cls,
             extra_format_validators=self.config.extra_format_validators,
             extra_media_type_deserializers=self.config.extra_media_type_deserializers,
-            strict_additional_properties=self.config.strict_additional_properties,
+            forbid_unspecified_additional_properties=self.config.additional_properties_default_policy == "forbid",
             security_provider_factory=self.config.security_provider_factory,
         )
 
@@ -446,7 +446,7 @@ def response_validator(self) -> ResponseValidator:
             spec_validator_cls=self.config.spec_validator_cls,
             extra_format_validators=self.config.extra_format_validators,
             extra_media_type_deserializers=self.config.extra_media_type_deserializers,
-            strict_additional_properties=self.config.strict_additional_properties,
+            forbid_unspecified_additional_properties=self.config.additional_properties_default_policy == "forbid",
             enforce_properties_required=self.config.response_properties_default_policy
             == "required",
         )
@@ -466,7 +466,7 @@ def webhook_request_validator(self) -> WebhookRequestValidator:
             spec_validator_cls=self.config.spec_validator_cls,
             extra_format_validators=self.config.extra_format_validators,
             extra_media_type_deserializers=self.config.extra_media_type_deserializers,
-            strict_additional_properties=self.config.strict_additional_properties,
+            forbid_unspecified_additional_properties=self.config.additional_properties_default_policy == "forbid",
             security_provider_factory=self.config.security_provider_factory,
         )
 
@@ -485,7 +485,7 @@ def webhook_response_validator(self) -> WebhookResponseValidator:
             spec_validator_cls=self.config.spec_validator_cls,
             extra_format_validators=self.config.extra_format_validators,
             extra_media_type_deserializers=self.config.extra_media_type_deserializers,
-            strict_additional_properties=self.config.strict_additional_properties,
+            forbid_unspecified_additional_properties=self.config.additional_properties_default_policy == "forbid",
             enforce_properties_required=self.config.response_properties_default_policy
             == "required",
         )
@@ -505,7 +505,7 @@ def request_unmarshaller(self) -> RequestUnmarshaller:
             spec_validator_cls=self.config.spec_validator_cls,
             extra_format_validators=self.config.extra_format_validators,
             extra_media_type_deserializers=self.config.extra_media_type_deserializers,
-            strict_additional_properties=self.config.strict_additional_properties,
+            forbid_unspecified_additional_properties=self.config.additional_properties_default_policy == "forbid",
             security_provider_factory=self.config.security_provider_factory,
             schema_unmarshallers_factory=self.config.schema_unmarshallers_factory,
             extra_format_unmarshallers=self.config.extra_format_unmarshallers,
@@ -526,7 +526,7 @@ def response_unmarshaller(self) -> ResponseUnmarshaller:
             spec_validator_cls=self.config.spec_validator_cls,
             extra_format_validators=self.config.extra_format_validators,
             extra_media_type_deserializers=self.config.extra_media_type_deserializers,
-            strict_additional_properties=self.config.strict_additional_properties,
+            forbid_unspecified_additional_properties=self.config.additional_properties_default_policy == "forbid",
             enforce_properties_required=self.config.response_properties_default_policy
             == "required",
             schema_unmarshallers_factory=self.config.schema_unmarshallers_factory,
@@ -548,7 +548,7 @@ def webhook_request_unmarshaller(self) -> WebhookRequestUnmarshaller:
             spec_validator_cls=self.config.spec_validator_cls,
             extra_format_validators=self.config.extra_format_validators,
             extra_media_type_deserializers=self.config.extra_media_type_deserializers,
-            strict_additional_properties=self.config.strict_additional_properties,
+            forbid_unspecified_additional_properties=self.config.additional_properties_default_policy == "forbid",
             security_provider_factory=self.config.security_provider_factory,
             schema_unmarshallers_factory=self.config.schema_unmarshallers_factory,
             extra_format_unmarshallers=self.config.extra_format_unmarshallers,
@@ -569,7 +569,7 @@ def webhook_response_unmarshaller(self) -> WebhookResponseUnmarshaller:
             spec_validator_cls=self.config.spec_validator_cls,
             extra_format_validators=self.config.extra_format_validators,
             extra_media_type_deserializers=self.config.extra_media_type_deserializers,
-            strict_additional_properties=self.config.strict_additional_properties,
+            forbid_unspecified_additional_properties=self.config.additional_properties_default_policy == "forbid",
             enforce_properties_required=self.config.response_properties_default_policy
             == "required",
             schema_unmarshallers_factory=self.config.schema_unmarshallers_factory,
diff --git a/openapi_core/unmarshalling/request/protocols.py b/openapi_core/unmarshalling/request/protocols.py
@@ -55,7 +55,7 @@ def __init__(
             MediaTypeDeserializersDict
         ] = None,
         security_provider_factory: SecurityProviderFactory = security_provider_factory,
-        strict_additional_properties: bool = False,
+        forbid_unspecified_additional_properties: bool = False,
         schema_unmarshallers_factory: Optional[
             SchemaUnmarshallersFactory
         ] = None,
@@ -91,7 +91,7 @@ def __init__(
             MediaTypeDeserializersDict
         ] = None,
         security_provider_factory: SecurityProviderFactory = security_provider_factory,
-        strict_additional_properties: bool = False,
+        forbid_unspecified_additional_properties: bool = False,
         schema_unmarshallers_factory: Optional[
             SchemaUnmarshallersFactory
         ] = None,
diff --git a/openapi_core/unmarshalling/request/unmarshallers.py b/openapi_core/unmarshalling/request/unmarshallers.py
@@ -120,7 +120,7 @@ def __init__(
             MediaTypeDeserializersDict
         ] = None,
         security_provider_factory: SecurityProviderFactory = security_provider_factory,
-        strict_additional_properties: bool = False,
+        forbid_unspecified_additional_properties: bool = False,
         schema_unmarshallers_factory: Optional[
             SchemaUnmarshallersFactory
         ] = None,
@@ -140,7 +140,7 @@ def __init__(
             format_validators=format_validators,
             extra_format_validators=extra_format_validators,
             extra_media_type_deserializers=extra_media_type_deserializers,
-            strict_additional_properties=strict_additional_properties,
+            forbid_unspecified_additional_properties=forbid_unspecified_additional_properties,
             schema_unmarshallers_factory=schema_unmarshallers_factory,
             format_unmarshallers=format_unmarshallers,
             extra_format_unmarshallers=extra_format_unmarshallers,
@@ -159,7 +159,7 @@ def __init__(
             extra_format_validators=extra_format_validators,
             extra_media_type_deserializers=extra_media_type_deserializers,
             security_provider_factory=security_provider_factory,
-            strict_additional_properties=strict_additional_properties,
+            forbid_unspecified_additional_properties=forbid_unspecified_additional_properties,
         )
 
     def _unmarshal(
diff --git a/openapi_core/unmarshalling/response/protocols.py b/openapi_core/unmarshalling/response/protocols.py
@@ -55,7 +55,7 @@ def __init__(
         extra_media_type_deserializers: Optional[
             MediaTypeDeserializersDict
         ] = None,
-        strict_additional_properties: bool = False,
+        forbid_unspecified_additional_properties: bool = False,
         enforce_properties_required: bool = False,
         schema_unmarshallers_factory: Optional[
             SchemaUnmarshallersFactory
@@ -92,7 +92,7 @@ def __init__(
         extra_media_type_deserializers: Optional[
             MediaTypeDeserializersDict
         ] = None,
-        strict_additional_properties: bool = False,
+        forbid_unspecified_additional_properties: bool = False,
         enforce_properties_required: bool = False,
         schema_unmarshallers_factory: Optional[
             SchemaUnmarshallersFactory
diff --git a/openapi_core/unmarshalling/schemas/factories.py b/openapi_core/unmarshalling/schemas/factories.py
@@ -38,7 +38,7 @@ def create(
         format_unmarshallers: Optional[FormatUnmarshallersDict] = None,
         extra_format_validators: Optional[FormatValidatorsDict] = None,
         extra_format_unmarshallers: Optional[FormatUnmarshallersDict] = None,
-        strict_additional_properties: bool = False,
+        forbid_unspecified_additional_properties: bool = False,
         enforce_properties_required: bool = False,
     ) -> SchemaUnmarshaller:
         """Create unmarshaller from the schema."""
@@ -54,7 +54,7 @@ def create(
             schema,
             format_validators=format_validators,
             extra_format_validators=extra_format_validators,
-            strict_additional_properties=strict_additional_properties,
+            forbid_unspecified_additional_properties=forbid_unspecified_additional_properties,
             enforce_properties_required=enforce_properties_required,
         )
 
diff --git a/openapi_core/unmarshalling/unmarshallers.py b/openapi_core/unmarshalling/unmarshallers.py
@@ -50,7 +50,7 @@ def __init__(
         extra_media_type_deserializers: Optional[
             MediaTypeDeserializersDict
         ] = None,
-        strict_additional_properties: bool = False,
+        forbid_unspecified_additional_properties: bool = False,
         enforce_properties_required: bool = False,
         schema_unmarshallers_factory: Optional[
             SchemaUnmarshallersFactory
@@ -75,7 +75,7 @@ def __init__(
             format_validators=format_validators,
             extra_format_validators=extra_format_validators,
             extra_media_type_deserializers=extra_media_type_deserializers,
-            strict_additional_properties=strict_additional_properties,
+            forbid_unspecified_additional_properties=forbid_unspecified_additional_properties,
             enforce_properties_required=enforce_properties_required,
         )
         self.schema_unmarshallers_factory = (
@@ -93,7 +93,7 @@ def _unmarshal_schema(self, schema: SchemaPath, value: Any) -> Any:
             schema,
             format_validators=self.format_validators,
             extra_format_validators=self.extra_format_validators,
-            strict_additional_properties=self.strict_additional_properties,
+            forbid_unspecified_additional_properties=self.forbid_unspecified_additional_properties,
             enforce_properties_required=self.enforce_properties_required,
             format_unmarshallers=self.format_unmarshallers,
             extra_format_unmarshallers=self.extra_format_unmarshallers,
diff --git a/openapi_core/validation/configurations.py b/openapi_core/validation/configurations.py
@@ -44,8 +44,8 @@ class ValidatorConfig:
             Extra media type deserializers.
         security_provider_factory
             Security providers factory.
-        strict_additional_properties
-            If true, treat schemas that omit additionalProperties as if
+        additional_properties_default_policy
+            If forbid, treat schemas that omit additionalProperties as if
             additionalProperties: false.
         response_properties_default_policy
             If true, response schema properties are treated as required during
@@ -70,7 +70,7 @@ class ValidatorConfig:
     security_provider_factory: SecurityProviderFactory = (
         security_provider_factory
     )
-    strict_additional_properties: bool = False
+    additional_properties_default_policy: Literal["allow", "forbid"] = "allow"
     response_properties_default_policy: Literal["optional", "required"] = (
         "optional"
     )
diff --git a/openapi_core/validation/request/protocols.py b/openapi_core/validation/request/protocols.py
@@ -49,7 +49,7 @@ def __init__(
             MediaTypeDeserializersDict
         ] = None,
         security_provider_factory: SecurityProviderFactory = security_provider_factory,
-        strict_additional_properties: bool = False,
+        forbid_unspecified_additional_properties: bool = False,
     ): ...
 
     def iter_errors(
@@ -85,7 +85,7 @@ def __init__(
             MediaTypeDeserializersDict
         ] = None,
         security_provider_factory: SecurityProviderFactory = security_provider_factory,
-        strict_additional_properties: bool = False,
+        forbid_unspecified_additional_properties: bool = False,
     ): ...
 
     def iter_errors(
diff --git a/openapi_core/validation/request/validators.py b/openapi_core/validation/request/validators.py
@@ -85,7 +85,7 @@ def __init__(
             MediaTypeDeserializersDict
         ] = None,
         security_provider_factory: SecurityProviderFactory = security_provider_factory,
-        strict_additional_properties: bool = False,
+        forbid_unspecified_additional_properties: bool = False,
     ):
 
         BaseValidator.__init__(
@@ -101,7 +101,7 @@ def __init__(
             format_validators=format_validators,
             extra_format_validators=extra_format_validators,
             extra_media_type_deserializers=extra_media_type_deserializers,
-            strict_additional_properties=strict_additional_properties,
+            forbid_unspecified_additional_properties=forbid_unspecified_additional_properties,
         )
         self.security_provider_factory = security_provider_factory
 
diff --git a/openapi_core/validation/response/protocols.py b/openapi_core/validation/response/protocols.py
@@ -47,7 +47,7 @@ def __init__(
         extra_media_type_deserializers: Optional[
             MediaTypeDeserializersDict
         ] = None,
-        strict_additional_properties: bool = False,
+        forbid_unspecified_additional_properties: bool = False,
         enforce_properties_required: bool = False,
     ): ...
 
@@ -85,7 +85,7 @@ def __init__(
         extra_media_type_deserializers: Optional[
             MediaTypeDeserializersDict
         ] = None,
-        strict_additional_properties: bool = False,
+        forbid_unspecified_additional_properties: bool = False,
         enforce_properties_required: bool = False,
     ): ...
 
diff --git a/openapi_core/validation/schemas/__init__.py b/openapi_core/validation/schemas/__init__.py
@@ -7,7 +7,7 @@
 from openapi_schema_validator import OAS32Validator
 
 from openapi_core.validation.schemas._validators import (
-    build_strict_additional_properties_validator,
+    build_forbid_unspecified_additional_properties_validator,
 )
 from openapi_core.validation.schemas.factories import SchemaValidatorsFactory
 
@@ -22,7 +22,7 @@
     OAS30WriteValidator,
     Proxy(
         partial(
-            build_strict_additional_properties_validator, OAS30WriteValidator
+            build_forbid_unspecified_additional_properties_validator, OAS30WriteValidator
         )
     ),
 )
@@ -31,15 +31,15 @@
     OAS30ReadValidator,
     Proxy(
         partial(
-            build_strict_additional_properties_validator, OAS30ReadValidator
+            build_forbid_unspecified_additional_properties_validator, OAS30ReadValidator
         )
     ),
 )
 
 oas31_schema_validators_factory = SchemaValidatorsFactory(
     OAS31Validator,
     Proxy(
-        partial(build_strict_additional_properties_validator, OAS31Validator)
+        partial(build_forbid_unspecified_additional_properties_validator, OAS31Validator)
     ),
     # NOTE: Intentionally use OAS 3.0 format checker for OAS 3.1 to preserve
     # backward compatibility for `byte`/`binary` formats.
@@ -50,6 +50,6 @@
 oas32_schema_validators_factory = SchemaValidatorsFactory(
     OAS32Validator,
     Proxy(
-        partial(build_strict_additional_properties_validator, OAS32Validator)
+        partial(build_forbid_unspecified_additional_properties_validator, OAS32Validator)
     ),
 )
diff --git a/openapi_core/validation/schemas/_validators.py b/openapi_core/validation/schemas/_validators.py
@@ -10,7 +10,7 @@
 from jsonschema.validators import extend
 
 
-def build_strict_additional_properties_validator(
+def build_forbid_unspecified_additional_properties_validator(
     validator_class: type[Validator],
 ) -> type[Validator]:
     properties_validator = validator_class.VALIDATORS.get("properties")
@@ -81,3 +81,42 @@ def iter_missing_additional_properties_errors(
     if extras:
         error = "Additional properties are not allowed (%s %s unexpected)"
         yield ValidationError(error % extras_msg(extras))
+
+
+def build_enforce_properties_required_validator(
+    validator_class: type[Validator],
+) -> type[Validator]:
+    properties_validator = validator_class.VALIDATORS.get("properties")
+
+    def enforce_properties(
+        validator: Any,
+        properties: Any,
+        instance: Any,
+        schema: Mapping[str, Any],
+    ) -> Iterator[Any]:
+        if properties_validator is not None:
+            yield from properties_validator(
+                validator, properties, instance, schema
+            )
+
+        if not validator.is_type(instance, "object"):
+            return
+
+        for prop_name, prop_schema in properties.items():
+            if prop_name not in instance:
+                if (
+                    isinstance(prop_schema, dict)
+                    and prop_schema.get("writeOnly") is True
+                ):
+                    continue
+                yield ValidationError(f"'{prop_name}' is a required property")
+
+    return cast(
+        type[Validator],
+        extend(
+            validator_class,
+            validators={
+                "properties": enforce_properties,
+            },
+        ),
+    )
diff --git a/openapi_core/validation/schemas/factories.py b/openapi_core/validation/schemas/factories.py
diff --git a/openapi_core/validation/validators.py b/openapi_core/validation/validators.py
diff --git a/tests/integration/validation/test_additional_properties_default_policy.py b/tests/integration/validation/test_additional_properties_default_policy.py
diff --git a/tests/unit/validation/test_schema_validators.py b/tests/unit/validation/test_schema_validators.py
