Can a Reentrancy Guard Be Bypassed?

A reentrancy guard can be bypassed if the attacker finds a way to call the critical function without triggering the guard mechanism, or if the guard is incorrectly implemented. For example, if the guard is only placed on the withdraw() function but the contract has another function, emergencyWithdraw() , that doesn't use the guard, the attacker could exploit the unprotected function.

It can also be bypassed in complex, multi-contract systems if the attacker can find a path that re-enters the contract through a function that calls the guarded function indirectly.