Common Smart Contract Bugs

Smart contracts hold real value and cant be patched casually once deployed, so a small mistake could be expensiive.

Bugs I look for first

• Reentrancy: an external call lets the caller re-enter before state is updated
• Missing access control on sensitive functions
• Integer and rounding errors in math
• Unchecked return values from low-level calls
• Price or oracle manipulation

My simple audit routine

1. Read the docs and work out what the contract is meant to do.
2. Run a static analyzer and note anything odd.
3. Read every external and public function by hand.
4. Write tests that try to break the rules.
5. Write up findings with a clear fix for each one.

More detail on each class is in the SWC Registry.