MorpheusAI

Summary

Openzeppelin has deprecated several functions and replaced with newer versions, with safeApprove being one of them.

Vulnerability Details

safeApprove() has been deprecated and the official OpenZeppelin documentation recommends using safeIncreaseAllowance() & safeDecreaseAllowance().

A deeper discussion on the deprecation of this function is in OZ issue #2219. The OpenZeppelin ERC20 safeApprove() function has been deprecated, as seen in the comments of the OpenZeppelin code.

There are 6 instances of this issue in contracts/L2TokenReceiver.sol.

Similar findings in other contests::

• Usage of deprecated safeApprove - Spearbit - Paladin.

• [L-07] Deprecated safeApprove() function - code4rena- Hubble contest.

• Use of deprecated function for setting token allowances - OPENZEPPELIN SECURITY- Pods Finance Ethereum Volatility Vault.

Impact

Using this deprecated function can lead to unintended reverts and potentially the locking of funds.

Tools Used

Manual Review.

Recommendations

Consider replacing safeApprove() with safeIncreaseAllowance() or safeDecreaseAl- lowance() instead (as suggested by the OpenZeppelin comment).