[USN-4247-2] python-apt regression

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==========================================================================
Ubuntu Security Notice USN-4247-2
January 22, 2020

python-apt regression
==========================================================================

A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 19.10
- Ubuntu 19.04
- Ubuntu 18.04 LTS
- Ubuntu 16.04 LTS

Summary:

USN-4247-1 introduced a regression in python-apt.

Software Description:
- python-apt: Python interface to libapt-pkg

Details:

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.

We apologize for the inconvenience.

Original advisory details:

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. (CVE-2019-15795)
It was discovered that python-apt could install packages from untrusted
repositories, contrary to expectations. (CVE-2019-15796)

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 19.10:
python-apt 1.9.0ubuntu1.3
python3-apt 1.9.0ubuntu1.3

Ubuntu 19.04:
python-apt 1.8.5~ubuntu0.3
python3-apt 1.8.5~ubuntu0.3

Ubuntu 18.04 LTS:
python-apt 1.6.5ubuntu0.2
python3-apt 1.6.5ubuntu0.2

Ubuntu 16.04 LTS:
python-apt 1.1.0~beta1ubuntu0.16.04.8
python3-apt 1.1.0~beta1ubuntu0.16.04.8

In general, a standard system update will make all the necessary changes.

References:
https://usn.ubuntu.com/4247-2
https://usn.ubuntu.com/4247-1
https://launchpad.net/bugs/1860606

Package Information:
https://launchpad.net/ubuntu/+source/python-apt/1.9.0ubuntu1.3
https://launchpad.net/ubuntu/+source/python-apt/1.8.5~ubuntu0.3
https://launchpad.net/ubuntu/+source/python-apt/1.6.5ubuntu0.2
https://launchpad.net/ubuntu/+source/python-apt/1.1.0~beta1ubuntu0.16.04.8