Patched code sample

# The following code demonstrates the fix for CVE-2026-59821.
# The vulnerability allowed privileged users to execute arbitrary Python code
# when creating or updating "Custom Code Guardrails" because the endpoint
# lacked proper sandboxing.
#
# The fix, represented below, is to process the user-provided code through a
# sandboxing mechanism (using RestrictedPython, as in the actual LiteLLM fix)
# that prevents access to unsafe modules and functions.

# Dependency: pip install RestrictedPython
from RestrictedPython import compile_restricted, safe_builtins
from RestrictedPython.PrintCollector import PrintCollector
import sys

def fixed_create_or_update_guardrail(custom_code: str):
    """
    Represents the fixed endpoint logic. It ensures any user-provided
    'custom_code' is executed within a sandbox before being activated,
    preventing it from accessing sensitive system resources.
    """
    # A safe environment is created, excluding dangerous built-ins.
    restricted_globals = {
        "__builtins__": safe_builtins,
        "_print_": PrintCollector, # A safe way to handle printing
    }
    try:
        # The core of the fix: The user's code is compiled in 'restricted' mode.
        # This will fail if the code tries to perform unsafe actions, like importing 'os'.
        byte_code = compile_restricted(
            custom_code,
            filename="<user_guardrail_code>",
            mode="exec",
        )

        # The 'exec' call is now safe because it runs the restricted bytecode,
        # which cannot access the underlying system.
        print(f"--- Attempting to execute code in sandbox: ---\n{custom_code}\n-------------------------------------------")
        exec(byte_code, restricted_globals, None)
        print("✅ SUCCESS: Code executed safely within the sandbox.\n")
        # In the real application, the validated code would now be saved/activated.

    except Exception as e:
        print(f"--- Attempting to execute code in sandbox: ---\n{custom_code}\n-------------------------------------------")
        print(f"❌ FAILED: Sandbox rejected the code. Reason: {e}\n", file=sys.stderr)


# --- Demonstration of the Fix ---

# 1. Malicious code attempting to import 'os' to access environment variables.
#    In the vulnerable version, this would execute. The fix prevents it.
malicious_code_attempt = 'import os\nprint(os.environ.get("SECRET_KEY"))'
fixed_create_or_update_guardrail(malicious_code_attempt)


# 2. Benign code performing a simple, safe calculation.
#    This is allowed by the sandbox and executes as expected.
benign_code_example = 'result = 100 * 2\nprint(f"Calculation result is: {result}")'
fixed_create_or_update_guardrail(benign_code_example)