solidity-security

Reentrancy vulnerabilities occur when a contract calls an external function before updating its state, allowing attackers to recursively drain funds. Apply the Checks-Effects-Interactions pattern: validate conditions first, update internal state second, then interact with external contracts. This ensures state changes complete before external calls can re-enter your code.

Integer overflow and underflow happen when arithmetic operations exceed fixed-size integer bounds, corrupting calculations and enabling exploits. Use OpenZeppelin Contracts' SafeMath library or Solidity 0.8+ built-in overflow checks, which revert transactions on unsafe arithmetic and prevent silent data corruption.

Access control restricts sensitive functions to authorized users, preventing unauthorized fund transfers or state changes. Implement role-based access using OpenZeppelin's AccessControl or ownership patterns, assigning specific roles with granular permissions and enforcing checks before executing protected operations.

Gas optimization reduces transaction fees while maintaining contract safety. Apply techniques like efficient storage layouts, batch operations, and avoiding redundant state reads—all supported by OpenZeppelin best practices—ensuring your optimizations don't weaken security patterns or introduce vulnerabilities.

Audit-ready contracts follow established security patterns, include clear documentation, and handle known attack vectors like reentrancy and front-running. Structure your code using Checks-Effects-Interactions, implement access control, apply safe arithmetic, and document design decisions so auditors can verify security comprehensively.

Front-running occurs when attackers observe pending transactions and submit higher-priority transactions to manipulate execution order or outcomes. Mitigate by minimizing sensitive state exposure, using commit-reveal schemes, avoiding transaction ordering dependencies, and designing contracts where transaction order doesn't leak value.