BIP66 fixed one source of transaction malleability and segwit, to my understanding, fixed the rest of the sources. Yet, there are still many common types of non-segwit transactions in use, like P2PKH P2SH(PWPKH) P2SH-multisig, are these subject to malleability attacks by a stranger?
I understand that even if someone knows how to do a malleability attack on these transactions, he might choose to answer "no" (or don't answer) to prevent these attacks. But, on the other hand, if a malleability attack on these common transactions was possible, I believe someone that wants to push for segwit adoption would have already build an app to systematically attack.