CVE-2017-14158
Scrapy 1.4 allows remote attackers to cause a denial of service (memory consumption) via large files because arbitrarily many files are read into memory, which is especially problematic if the files are then individually written in a separate thread to a slow storage resource, as demonstrated by interaction between dataReceived (in core/downloader/handlers/http11.py) and S3FilesStore.
Source: CVE-2017-14158