The support for the Kerberos MSSFU extensions [1] is now extended to cross-realm environments. By leveraging the Kerberos cross-realm referrals enhancement introduced in the context of JDK-8215032, the 'S4U2Self' and 'S4U2Proxy' extensions may be used to impersonate user and service principals located on different realms. [1] - https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-sfu/3bff5864-8135-400e-bdd9-33b552051d94