USN-5179-1 fixed vulnerabilities in BusyBox. This update provides the corresponding updates for Ubuntu 16.04 ESM.
Original advisory details:
It was discovered that BusyBox incorrectly handled certain malformed gzip archives. If a user or automated system were tricked into processing a specially crafted gzip archive, a remote attacker could use this issue to cause BusyBox to crash, resulting in a denial of service, or possibly execute arbitrary code. (CVE-2021-28831)
1:1.22.0-15ubuntu1.4+esm1