Patched code sample

import json
from typing import Any, Dict

def _is_public_prompt(prompt_identifier: str) -> bool:
    """
    Checks if a prompt identifier refers to a public prompt by looking for
    the 'owner/name' format. This is the key to identifying potentially
    untrusted content from an external party.
    """
    return "/" in prompt_identifier

def fixed_langsmith_pull_deserializer(
    prompt_identifier: str, manifest_data: bytes
) -> Dict[str, Any]:
    """
    This function provides a conceptual representation of the fix for
    CVE-2026-45134 in the LangSmith Python SDK.

    The vulnerability was that manifests from public prompts were deserialized
    with a method that could execute arbitrary code. The fix is to
    differentiate public prompts and parse them using a safe method.
    """
    # THE FIX:
    # Before deserializing, check if the prompt is from a public, untrusted source.
    if _is_public_prompt(prompt_identifier):
        # If the prompt is public, strictly use a safe deserializer like
        # json.loads. This prevents malicious, non-JSON payloads (such as a
        # pickled object) from being processed and executed.
        try:
            return json.loads(manifest_data)
        except json.JSONDecodeError as e:
            # By rejecting any manifest that is not valid JSON, the attack
            # vector of using an alternative, unsafe serialization format is closed.
            raise ValueError(
                "Public prompt manifests must be valid JSON."
            ) from e
    else:
        # For private prompts (within the user's own organization), the
        # source is considered trusted. A robust modern implementation would
        # likely use a safe deserializer here as well for defense-in-depth.
        return json.loads(manifest_data)