Just had a look again apparently the issue is still openhttps://github.com/openhab/openhab-addons/issues/8872
But anyway the use of Knx secure and openhab kind of defeats the purpose here because what are you trying to protect ? Do you have very sensitive data running on your bus ? Openhab is not secure by design and giving it the key make this whole thing unsecure again if the attack is to steal that information. Overall a good blocked Ethernet router without any allowed ports and just good firewall rules for your automation network goes way more than the marketing from Knx to secure your data.
I also have secure routers devices and i just disable all that crap because if the attacker is already in the network probably the automation side of thing is the last thing you need to worry about i would look more into sensitive data documents photos clips etc. Also let’s say he is inside your bus and let’s say your garage door is on the bus if safety is your concern and you don’t have a classical offline siren keypad sensor alarm system then it’s your fault for not having residency.
I am not trying to discourage the use of such features any extra layer of security is good but by giving openhab the key it defeats the purpose it’s like giving a child the key and hoping that the bad guy doesn’t look at him to read it…