Language: Python
Label: vulnerable
CWE: CWE-22 \u2014 Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.

Code:
    def __init__(self, config, md):
        """Initialize."""

        base = config.get('base_path')
        if isinstance(base, str):
            base = [base]
        self.base_path = base
        self.encoding = config.get('encoding')
        self.check_paths = config.get('check_paths')
        self.auto_append = config.get('auto_append')
        self.url_download = config['url_download']
        self.url_max_size = config['url_max_size']
        self.url_timeout = config['url_timeout']
        self.url_request_headers = config['url_request_headers']
        self.dedent_subsections = config['dedent_subsections']
        self.tab_length = md.tab_length
        super(SnippetPreprocessor, self).__init__()