What are the key security concerns when developing with Solidity?

The major security concerns during Solidity development include reentrancy attacks, wherein malicious contracts leverage recursive calls to drain funds, and integer overflows or underflows, which may lead to unexpected behaviors. Moreover, developers must ensure proper access control to prevent unauthorized actions and validate user inputs to avoid injection vulnerabilities. Also, the gas limit and block size constraints may affect the execution of a smart contract. Using well-tested libraries, following best practices, and extensive testing using tools like MythX or Slither helps mitigate risks and improve security for Solidity smart contracts.