What Are the Biggest Smart Contract Vulnerabilities in Crypto History?
The DAO hack: $60 million stolen in 2016
The year 2016 marked a significant event in the cryptocurrency world when The DAO, a decentralized autonomous organization, fell victim to a major hack. This incident resulted in the theft of approximately $60 million worth of Ether, sending shockwaves through the Ethereum community. The attack exploited a vulnerability in The DAO's smart contract code, allowing the hacker to drain funds from the organization's wallet. This event not only highlighted the potential risks associated with smart contracts but also led to a contentious hard fork in the Ethereum blockchain. The aftermath of the hack resulted in the creation of Ethereum Classic, which maintained the original, unaltered history of the Ethereum blockchain. The DAO hack serves as a cautionary tale for the crypto industry, emphasizing the importance of robust security measures and thorough code audits. It also sparked debates about the immutability of blockchain technology and the role of human intervention in decentralized systems.
Parity wallet freeze: $300 million locked in 2017
In 2017, the cryptocurrency world was rocked by a significant incident involving Parity Technologies' multi-signature wallets. A critical software vulnerability led to the freezing of approximately $300 million worth of Ether, Ethereum's native cryptocurrency. This event occurred on November 8, when a GitHub user known as "devops199" inadvertently triggered a flaw in the Parity wallet code. The bug affected over 500 multi-signature wallets, rendering their funds completely inaccessible. This incident followed a previous security breach in July of the same year, where a hacker exploited a different vulnerability to steal $32 million from Parity wallets. The table below illustrates the impact of these two Parity wallet incidents:
| Date | Incident | Amount Affected |
|---|---|---|
| July 2017 | Hacking of Parity wallets | $32 million |
| Nov 2017 | Freezing of Parity wallets | $300 million |
The November freeze was particularly troubling as it was not the result of malicious intent but rather an accidental triggering of a vulnerability. Despite extensive investigation, a resolution to unlock the frozen funds has not been found, leaving affected users in a state of limbo. This incident underscores the critical importance of rigorous security measures and code audits in the rapidly evolving world of cryptocurrency and blockchain technology.
Centralized exchange hacks: Over $1 billion lost since 2018
The cryptocurrency industry has been plagued by a series of devastating hacks targeting centralized exchanges since 2018, resulting in staggering financial losses exceeding $1 billion as of 2025. These incidents have exposed critical vulnerabilities in security protocols, shaking investor confidence and highlighting the need for robust safeguards in the digital asset ecosystem. The frequency and magnitude of these attacks have prompted widespread concern among industry participants and regulators alike.
To illustrate the severity of the situation, consider the following data:
| Year | Number of Major Hacks | Estimated Losses (USD) |
|---|---|---|
| 2018 | 3 | $875 million |
| 2019 | 2 | $292 million |
| 2020 | 4 | $300 million |
| 2021 | 5 | $611 million |
| 2022 | 3 | $398 million |
These figures underscore the persistent threat faced by centralized exchanges and the urgent need for enhanced security measures. The cryptocurrency community has responded with intensified efforts to develop more secure infrastructure and implement advanced protection mechanisms. However, the ongoing nature of these attacks suggests that much work remains to be done to safeguard digital assets effectively.