Language: Python
Label: safe
CWE: CWE-94 \u2014 Improper Control of Generation of Code ('Code Injection')
The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.

Code:
def _raise_if_restricted_key(key):
    # Prevent access to dunder-methods since this could expose access to globals through leaky
    # attributes such as obj.__init__.__globals__.
    if len(key) > 4 and key.isascii() and key.startswith("__") and key.endswith("__"):
        raise KeyError(f"access to restricted key {key!r} is not allowed")