Python pickle serialization

Description

This application uses Python's pickle module to deserialize data from untrusted user input. The pickle module can execute arbitrary Python code during the deserialization process, making it inherently unsafe when processing data from external sources. This vulnerability occurs when user-controlled data is passed to pickle.loads() or pickle.load() without proper validation.

Remediation

Immediately stop using pickle to deserialize untrusted data. Implement one of the following secure alternatives:

1. Use JSON for data serialization (Recommended)
Replace pickle with the json module, which only handles basic data types and cannot execute code:

import json

# Instead of:
# data = pickle.loads(user_input)

# Use:
data = json.loads(user_input)

import hmac
import pickle
from hashlib import sha256

SECRET_KEY = b'your-secret-key-here'  # Store securely

def safe_pickle_loads(signed_data):
    signature = signed_data[:32]
    pickled_data = signed_data[32:]
    expected_sig = hmac.new(SECRET_KEY, pickled_data, sha256).digest()
    if not hmac.compare_digest(signature, expected_sig):
        raise ValueError('Invalid signature')
    return pickle.loads(pickled_data)

References

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