What's relationship to each address other in Bitcoin Core? I just made two and more address in Bitcoin Core wallet. 


Is there any relationship to each address? Like based on seedphase? or Just literally making 'random' address?
If so, an attacker can hack the other address if knows one of private key?


Thank you for your answer.
Is there any relationship to each address? Like based on seedphase? or Just literally making 'random' address?


It depends.

In old versions of Bitcoin Core, addresses were just randomly generated and the private keys stored in wallet.dat.

Newer wallets that implement BIP32 derive all of the wallet private keys from one master private key.




  If so, an attacker can hack the other address if knows one of private key?


If an attacker knows your 12 seed words, they can derive the private keys in your wallet and steal all of your coins, but this is no worse than an attacker having your wallet.dat.