Patched code sample

import pydantic
from typing import Optional

# The CVE describes a scenario where a user can pass `trust_remote_code=True`
# in a collection update. In a modern Python application using Pydantic for
# validation, the fix is to add a validator that explicitly forbids this
# parameter from being set to True by a user.
#
# This Pydantic model represents the part of the API payload that would be
# validated. The validator function is the specific fix.

class CollectionUpdateMetadata(pydantic.BaseModel):
    """
    A Pydantic model to validate metadata updates for a collection.
    """
    # Other metadata fields would be defined here...

    # The field that an attacker would attempt to manipulate.
    trust_remote_code: Optional[bool] = None

    @pydantic.validator("trust_remote_code")
    def prevent_trust_remote_code_via_api(cls, v: Optional[bool]) -> Optional[bool]:
        """
        FIX: This validator prevents a user from setting `trust_remote_code`
        to True. If the value is True, it raises a ValueError, which stops
        the request from being processed and prevents the code injection.
        This setting should only be configurable on the server side by an
        administrator, not via the public API.
        """
        if v is True:
            raise ValueError(
                "'trust_remote_code' cannot be set to True via the API. "
                "This option is restricted to server-side configuration."
            )
        return v

# --- DEMONSTRATION OF THE FIX IN ACTION ---
# This part would not be in the application code but demonstrates how the
# validator works.

# 1. An attacker sends a malicious payload attempting to set trust_remote_code=True.
malicious_payload = {"trust_remote_code": True}

try:
    # The validation will fail here due to the validator.
    CollectionUpdateMetadata.parse_obj(malicious_payload)
except pydantic.ValidationError as e:
    print("Fix successful: Attacker's payload was correctly rejected.")
    print(f"Reason: {e}\n")


# 2. A legitimate user sends a payload without this flag or with it set to False.
legitimate_payload_1 = {}
legitimate_payload_2 = {"trust_remote_code": False}

try:
    # This will pass validation.
    CollectionUpdateMetadata.parse_obj(legitimate_payload_1)
    CollectionUpdateMetadata.parse_obj(legitimate_payload_2)
    print("Fix confirmed: Legitimate payloads are processed correctly.")
except pydantic.ValidationError:
    print("Error: Legitimate payload was incorrectly rejected.")