tx-malleability who re-signed the tx?
Actually, nobody else can create a valid signature for your transaction inputs, as they do not possess the private keys to do so.

When a transaction is malleated by a third party, it is not re-signed, merely it's signature is changed. ECDSA signatures are malleable, in that taking the negative of number S (modulo the curve order) does not invalidate them. As the TXID is created by hashing the complete transaction data, this will result in a new valid transaction with identical payload except for a new TXID.