From Reentrancy Attacks to Unchecked External Calls, these flaws continue to plague DeFi, NFTs, and smart contract-based applications. This is exactly why OWASP released its updated list of the top 10 Smart Contract vulnerabilities, highlighting the most critical security risks affecting blockchain security. The 2025 edition introduces updated threats, ranking adjustments, and the removal of some previous vulnerabilities, reflecting the evolving threat landscape.
Let’s dive into OWASP SC Top 10 [2025 Edition]
1. Access Control Vulnerabilities: Poorly implemented permissions and role-based access controls allow attackers to gain unauthorized control over smart contracts.
Securing #1 on the list AGAIN shows that this is the number one cause of smart contract hacks — from unauthorized admin actions to private function exploits.
We too believe that poorly implemented onlyOwner modifiers, lack of proper role-based access control (RBAC), and exposed admin functions are still the biggest threat to the smart contract.
2. Price Oracle Manipulation: Attackers manipulate price oracles to artificially inflate or deflate asset values, tricking DeFi protocols into faulty trades, liquidations, or unfair payouts.
DeFi protocols heavily rely on oracles, and manipulating price feeds can cause massive financial losses (flash loan exploits, price distortions, etc.). That is the reason why this vulnerability has been added to the list this year.
We’ve seen countless exploits where attackers manipulate Uniswap TWAPs, Chainlink Oracles, and custom price feeds to drain liquidity pools.
3. Logic Errors: Flaws in business logic or miscalculations in smart contracts that can be exploited for financial gain or unexpected behavior.
Logic flaws (often known as Business Logic Flaws) don’t always look like security risks but can be exploited for economic gains like faulty reward distribution and incorrect fee calculations. We have seen an increase in Logic Errors and no doubt it climbed from #7 to #3 this year.
Security is not just about bugs — it’s about ensuring contracts behave as expected, even under edge cases.
4. Lack of Input Validation: Contracts that fail to validate user input are vulnerable to integer overflows, reentrancy, and unexpected function execution.
Added new to the list, lack of input validation can lead to integer overflows, unintended state changes, and function reentrancy.
There’s a golden rule that we have set up at Resonance, that is: “Validate everything! Assume every function input is malicious and sanitize accordingly.”
5. Reentrancy Attacks: An attacker calls back into the same contract before its initial function execution is completed, allowing them to drain funds or alter contract states.
This classic solidity vulnerability might have fallen from #1 to #5 but still remains a major threat, but better tooling and design patterns like Checks-Effects-Interactions and Reentrancy Guards have made it less common.
Developers still underestimate reentrancy risks — especially in yield farming and lending protocols, but this vulnerability should still be taken under consideration.
6. Unchecked External Calls: Contracts that call untrusted external contracts without verifying the return value or handling failures properly, leading to unexpected behavior.
Smart contracts often interact with untrusted contracts — and failing to check return values can lead to silent failures or unintended execution. This vulnerability has been the reason behind many hacks and that is the reason why it climbed from #10 to #6 this year.
It’s simple: If you don’t validate external calls, attackers will exploit them!
7. Flash Loan Attacks: Attackers borrow large amounts of assets without collateral and manipulate DeFi protocols within a single transaction before repaying the loan.
This term has been quite trendy for the last two years and you must have heard it somewhere or the other but many don’t know that flash loans aren’t a bug but a feature that attackers can abuse to manipulate markets, drain liquidity pools, and even exploit pricing mechanisms.
This vulnerability has been commonly seen in the crypto world for a good amount of time now and no doubt it is added to the list. Devs need to design with flash loans in mind — not just react when they’re exploited.
8. Integer Overflow & Underflow: Arithmetic calculations exceeding the data type limits cause unintended behavior, allowing attackers to manipulate balances and contract states.
Solidity 0.8+ prevents integer overflow/underflow by default, but older contracts and custom math libraries are still vulnerable to this vulnerability. If you still rely on Solidity <0.8 or outdated SafeMath, it’s time for you to upgrade!
As most of the devs keep their tools in the arsenal upgraded, we have seen a significant drop in the hacks that are caused by Integer Overflow/Underflow and that is the reason why this vulnerability was adjusted from #2 to #8 this year.
9. Insecure Randomness: Blockchain-generated random numbers (RNG) aren’t truly random, making them predictable & exploitable for lotteries, gambling, and gaming contracts and attackers can manipulate block hashes, timestamp dependencies, or miner-exposed randomness.
We always advise using Verifiable Random Function (VRF) solutions like Chainlink VRF to avoid manipulation.
10. Denial of Service (DoS) Attacks: Attackers consume excessive gas or exploit expensive contract functions to make a smart contract unusable or extremely slow.
DoS attacks feel old-school and don’t directly steal funds but they can halt protocol operations, freeze funds, or block user transactions. Things like gas griefing, contract size limits, and block stuffing attacks can cripple DeFi protocols and can hamper their reputation as DoS makes user experience really worse.
As almost every dev designs for failure resilience and also plants solutions like firewalls, load balancers, WAFs, etc., DoS is not a BIG problem these days and that is the reason why it stands at #10 in the list this year.
What changed from 2023? What was removed from the list?
Some vulnerabilities from the 2023 list are missing in 2025. Here’s what got removed and why:
- Front-Running Attacks: EIP-1559 and private mempools (flashbots, MEV relays) have reduced front-running risks. However, MEV remains an issue, just not an OWASP SC Top 10 priority anymore.
- Timestamp Dependence: Modern randomness solutions like Chainlink VRF reduce reliance on block timestamps for randomness, making this a less critical attack vector.
- Gas Limit Vulnerabilities: Gas optimization techniques and EIP improvements have made gas-related DoS attacks less frequent. However, poorly optimized smart contracts can still be exploited if they do not handle gas limits properly.
While the OWASP Smart Contract Top 10 (2025 Edition) highlights the most critical vulnerabilities, it’s not an exhaustive list of all possible security risks. Hackers don’t limit themselves to just 10 attack vectors — neither should your security strategy.
Cybersecurity professionals must go beyond the OWASP list and conduct comprehensive security assessments, identifying risks that may not yet be widely documented. Social engineering, phishing attacks, protocol misconfigurations, governance manipulation, and human errors are equally dangerous threats that shouldn’t be overlooked.
At Resonance Security, we don’t just check for the OWASP Top 10 vulnerabilities — we analyze, simulate, and defend against all possible attack vectors, ensuring complete security for your blockchain project.
If you’re looking for a full-spectrum cybersecurity company to elevate your security posture and safeguard your project, Resonance Security has you covered. Reach out to us at support@resonance.security.
Let’s make web3 a secure space to explore!
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