That is not the case. That would be ECB mode. CBC stands for cipher-block-chaining. Where you xor the plaintext with the ciphertext of the last block before enc

That is not the case. That would be ECB mode. CBC stands for cipher-block-chaining. Where you xor the plaintext with the ciphertext of the last block before encryption specifically to prevent identical blocks from yielding identical ciphertext. There are some issues with CBC regarding the fact that it can't really be parralelized. It also lacks authentication as opposed to the newer GCM mode. In general though, AES-256 CBC is essentially THE standard best practice proven form of encryption.