Smart Contracts

How decentralized apps are built, secured, and governed.

Updated Oct 21, 2026GaiaEx Academy Editorial

In this lesson

Common smart-contract risks
What an audit does

Key takeaways

1Immutable code means bugs can be catastrophic
2Audits hunt for vulnerabilities before launch
3Reentrancy and bad approvals are classic exploits

Lesson summary

Smart-contract security is about preventing code from doing unintended things with real assets.

Mental model

Smart Contracts in plain terms

Smart-contract security is about preventing code from doing unintended things with real assets. An audit improves confidence, but it is not insurance.

Common smart-contract risks
What an audit does

Mechanics

How to reason about smart contracts

Auditors review logic, permissions, edge cases, and known vulnerability classes.

Bug bounties and time in production provide additional evidence.

Upgrade keys and admin roles can be as important as the code itself.

Immutable code means bugs can be catastrophic
Audits hunt for vulnerabilities before launch
Reentrancy and bad approvals are classic exploits

Example

Smart Contracts, applied

A reentrancy bug can let an attacker call back into a contract before balances are updated, draining funds if protections are missing.

RememberDecision rule: Treat audits as evidence, then verify deployment, admin controls, and live incident history.

Common mistakes

How smart contracts trips learners up

An audit logo on a website is not enough. Users need to know what version was audited and whether the deployed contract matches it.

Risk notes

Before you rely on smart contracts

Reentrancy, oracle manipulation, unchecked permissions, bad upgrades, and infinite approvals can create catastrophic loss paths.

Check audit scope.
Review admin or upgrade powers.
Avoid unnecessary unlimited approvals.

Practice

Make smart contracts stick

Check audit scope.
Review admin or upgrade powers.
Avoid unnecessary unlimited approvals.

Review

Key terms

Oracle: A service that feeds real-world data (like prices) to smart contracts on-chain.
Smart Contract: Self-executing code on a blockchain that runs exactly as written when conditions are met.
Oracle Manipulation: Exploiting a faulty price feed to drain a protocol.
Blockchain: A shared, append-only ledger replicated across many computers, secured by cryptography and consensus.
Consensus Mechanism: The process by which a distributed network agrees on the valid state of the ledger (e.g. PoW, PoS).

Source notes