What I see is that even after upgrade to the latest version I still have OSX complaining about ScreenOS using weak ciphers. I can override this warning and connect anyway.
The admin > management option to select ciphers has no additional options.
Since Juniper is stating above that ScreenOS is not vulnerable to the CVE, you might open a ticket and get their details from JTAC for your auditors instead of going through the accepted risk process.