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 (denial of service). (CVE-2020-11612)
Original advisory details:
It was discovered that Netty had HTTP request smuggling vulnerabilities. A remote attacker could used it to extract sensitive information. (CVE-2019-16869, CVE-2019-20444, CVE-2019-20445, CVE-2020-7238)