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

python-apt regression
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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