How Does a Successful Collision Attack Impact the Reliability of a Merkle Root?

A successful collision attack would allow an attacker to find two different sets of transactions that result in the same Merkle Root. This means an attacker could replace a legitimate transaction with a fraudulent one, or vice-versa, without altering the final Merkle Root in the block header.

If the root remains the same, light clients relying on the Merkle Proof would incorrectly verify the fraudulent block as valid, severely compromising data integrity.