Ubuntu Security Notice 4247-2 - USN-4247-1 fixed vulnerabilities in python-apt. The updated packages caused a regression when attempting to upgrade to a new Ubuntu release. This update fixes the problem. It was discovered that python-apt would still use MD5 hashes to validate certain downloaded packages. If a remote attacker were able to perform a man-in-the-middle attack, this flaw could potentially be used to install altered packages. It was discovered that python-apt could install packages from untrusted repositories, contrary to expectations. Various other issues were also addressed.
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