Smart contracts are unusual software: they hold real value, they are public, and they usually cannot be patched once deployed. That combination makes security review part of development, not a step at the end.
Some vulnerability classes appear again and again. Reentrancy lets a malicious contract call back into yours before your state is updated. Access control mistakes leave privileged functions open to anyone. Arithmetic issues can still occur despite modern compiler protections, particularly in custom maths.
Price and oracle manipulation deserve special attention in decentralised finance. If a contract relies on a spot price that can be moved within a single transaction, flash loans can turn that into an attack.
Upgradeability and admin keys are another frequent weak point. A well-audited contract controlled by a single unprotected key is only as safe as that key.
Good practice starts early: keep contracts simple, use well-tested libraries, write thorough tests including failure cases and run static analysis and fuzzing as part of every build.
An independent audit then adds fresh eyes on logic and economic design. It reduces risk, but it does not remove it, so plan monitoring, a response process and staged deployment.
Treat every audit finding as a lesson for the next contract, not only a fix for this one.