When I serialize a HTML document including elements with ARIA related attributes,serialize method drops them off as a result of sanitization.

importhtml5libdoc='<div>the description</div><span aria-describedby="foo">bar</span>'print(html5lib.serialize(html5lib.parseFragment(doc),sanitize=True,quote_attr_values='always'))# <div>the description</div><span>bar</span>

ARIA related attributes are not dangerous for my understanding, soserialize method should keep them even if the parametersanitize isTrue.