NULL pointer dereference in TagSection.keys() in python-apt on APT-based Linux systems allows a local attacker to cause a denial of service (process crash) via a crafted deb822 file with a malformed non-UTF-8 key.

USN-4247-1 fixed several vulnerabilities in python-apt. This update provides the corresponding updates for Ubuntu 12.04 ESM and Ubuntu 14.04 ESM. 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 machine-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)

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 machine-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)