Marshmallow has DoS in Schema.load(many)

Impact

Schema.load(data, many=True) is vulnerable to denial of service attacks. A moderately sized request can consume a disproportionate amount of CPU time.

Patches

4.1.2, 3.26.2

Workarounds

# Fail fast
def load_many(schema, data, **kwargs):
    if not isinstance(data, list):
        raise ValidationError(['Invalid input type.'])
    return [schema.load(item, **kwargs) for item in data]