A system authentication measure could be bypassed. Goldberg, Miro Haller, Nadia Heninger, Mike Milano, Dan Shumow, Marc
Stevens, and Adam Suhl discovered that Kerberos incorrectly authenticated
certain responses. An attacker able to intercept communications between a
RADIUS client and server could possibly use this issue to forge responses,
bypass authentication, and access network devices and services
https://ubuntu.com/security/notices/USN-7257-1