CVE-2019-15796: Improper Verification of Cryptographic Signature

Python-apt does not check if hashes are signed in Version.fetch_binary() and Version.fetch_source() of apt/package.py or in _fetch_archives() of apt/cache.py in version 1.9.3ubuntu2 and earlier. This allows downloads from unsigned repositories which shouldn’t be allowed and has been fixed in verisions 1.9.5, 1.9.0ubuntu1.2, 1.6.5ubuntu0.1, 1.1.0~beta1ubuntu0.16.04.7, 0.9.3.5ubuntu3+esm2, and 0.8.3ubuntu7.5.