You can change default encryption security to the more secure RC4-HMAC standard, if you fulfill certain prerequisites.
default_tgs_enctypes = rc4-hmac
default_tkt_enctypes = rc4-hmac
That is, replace the recommended des-cbc-md5 des-cbc-crc on those two lines with rc4-hmac.
After changing this setting in your krb5.ini file, you might have to run (or re-run) the step to create the keytab (re-running ktpass or ktab is not needed if you have already run ktpass ktab on WebLogic Java 6 or later setups).
Make sure that the Kerberos identity user account you have set up does not have Use DES encryption types for this account selected. If it is already selected, then you must unselect it and re-enter the password.
It is not possible for the same SPN/identity user account to support both DES and RC4-HMAC security. It must be one or the other.