A comprehensive survey of smart contract security highlights reentrancy attack as one of the most common and famous types of attacks.

While OpenZeppelin's ReentrancyGuard can mitigate this attack, it has fundamental limitations that make it difficult to prevent all reentrant calls.

Spherex suggests a different approach by incorporating a proxy contract to prevent reentrant calls. The use of a proxy contract requires minimal extra code and is upgradeproof, resulting in a lean and clean implementation.

However, fine-grained control over function selectors is yet to be implemented.

>>The Reentrancy Proxy is available for free use by the community.