What Is the Risk of a Malleated Transaction to the Original Sender?

The primary risk of a malleated transaction to the original sender was in the context of double-spending attempts in multi-stage protocols. If the sender relied on the original TXID to confirm a subsequent action (like receiving a refund or a linked payment), the malleated TXID could cause that subsequent action to fail.

In the case of an exchange, a user could claim they never received a withdrawal because the TXID was changed, leading to a fraudulent refund. The risk was less about the underlying transfer and more about protocol failure.