# Tutorial 55: AssetIn == AssetOut, FromToken == ToToken

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In decentralized finance (DeFi), asset swaps are a common and fundamental feature, allowing users to exchange one token for another. These swaps typically occur on decentralized exchanges (DEXs) or other protocols that support liquidity pools. However, incorrect validation or insufficient checks during these operations can lead to vulnerabilities where the **input token (fromToken)** and the **output token (toToken)** are treated as identical, allowing malicious actors to exploit the protocol.

When protocols fail to enforce proper checks to ensure that the `fromToken` and `toToken` are not the same, it opens up various attack vectors. In this section, we’ll dive into how this issue can arise, its impact, and how attackers can leverage it to drain liquidity or bypass restrictions. We'll also explore effective mitigation techniques to safeguard against such vulnerabilities.


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