USN-5378-1 fixed a vulnerability in Gzip. This update provides the corresponding update for Ubuntu 14.04 ESM and 16.04 ESM.
Original advisory details:
Cleemy Desu Wayo discovered that Gzip incorrectly handled certain filenames. If a user or automated system were tricked into performing zgrep operations with specially crafted filenames, a remote attacker could overwrite arbitrary files.