In DeFi, deposits, loans, and exchanges are all handled automatically by smart contracts. There’s no human review, and no customer service team that can recover funds sent to the wrong address. When a contract is written correctly, it’s the most reliable rulebook; when it’s written incorrectly, its vulnerabilities are just as meticulously “executed.”

Coin mentioned in the article: $ETH quoted at 2500.87 (24h +2.6%).

Code is law—and so are vulnerabilities:

Once a smart contract is deployed on-chain, it executes automatically according to its code. This brings transparency and predictability: anyone can read the code, and the rules of an immutable contract won’t change just because someone changes their mind.

Conversely, once someone discovers and exploits a vulnerability in the code, funds can be drained in just a few transactions and are very difficult to recover. The DAO in 2016 is one example: its contract was attacked due to a reentrancy vulnerability. Ethereum then addressed the issue with a hard fork, while the unforked original chain continued as Ethereum Classic (ETC).

What does an audit actually cover?

A security audit is an examination of a particular version of code, carried out by a third-party security team at a specific point in time. An audit report generally lists the issues found, how severe each one is, and whether the project team has fixed them.

Common checks include reentrancy, access-control errors, calculation precision issues, and the possibility of oracle manipulation. Audits help find and reduce these common vulnerabilities, but they are limited by time, staffing, and scope.

Why can things still go wrong after an audit?

First, an audit only covers the specified code. Contracts outside that scope and features added later aren’t included. If the code is changed after the audit, or the deployed version differs from the audited version, the audit’s conclusions may no longer apply.

Second, some risks don’t come from the code itself: an oracle or another protocol the project depends on could fail; an administrator’s key, which controls upgrades, could be stolen; or a website’s frontend could be tampered with to trick users into signing malicious transactions. Any of these could lead to losses.

What can everyday users do?

When reading an audit report, pay attention to its date and scope, and to any issues that haven’t been fixed. Don’t just look for the words “audited.” You can also check whether the contract can be upgraded unilaterally and whether upgrade permissions are controlled by a multisig and a timelock.

Protocols with a long track record and a lot of funds tested in practice are generally considered more reliable, but that doesn’t mean they’re vulnerability-free. So only put into DeFi what you can afford to lose, spread large sums across different protocols, and remember to revoke permissions for protocols you no longer use.

A final word:

An audit is the starting point for security, not the finish line. It’s more realistic to treat smart contract risk as a cost of participating in DeFi than to trust the words “audited.” Every potential return comes with risk, so think carefully about how much you could lose in the worst case.

What would you like to hear about next? DeFi or something else?

This isn’t investment advice. Don’t copy what I do.