Ubuntu Security Notice 4600-2 – USN-4600-1 fixed multiple vunerabilities in Netty 3.9. This update provides the corresponding fixes for CVE-2019-20444, CVE-2019-20445 for Netty. Also it was discovered that Netty allow for unbounded memory allocation. A remote attacker could send a large stream to the Netty server causing it to crash. Various other issues were also addressed.