According to Cointelegraph, the offline computation protocol Truebit recently experienced a $26 million exploit due to a flaw in its smart contract. This vulnerability allowed an attacker to mint tokens at nearly zero cost, leading to a dramatic 99% crash in the value of the Truebit (TRU) token. The breach underscores the persistent security risks that even long-standing blockchain projects face. Blockchain security firm SlowMist conducted a post-mortem analysis, revealing that the exploit stemmed from a loophole in the protocol’s smart contract logic. This flaw enabled the attacker to mint a significant number of tokens without incurring any ETH costs. SlowMist identified a lack of overflow protection in an integer addition operation within the Purchase contract of Truebit Protocol. This oversight resulted in incorrect calculations of the ETH required to mint TRU tokens. Consequently, the smart contract’s price calculations were erroneously reduced to zero, allowing the attacker to deplete the contract’s reserves by minting $26 million worth of tokens at minimal cost. The contract was compiled with Solidity 0.6.10, a version that lacked built-in overflow checks, leading to a "silent overflow" when calculations exceeded the maximum value of "uint256," causing the result to wrap around a small value near zero.
The incident highlights the vulnerability of even well-established protocols to hacking threats. Truebit, launched on the Ethereum mainnet in April 2021, is not alone in facing such challenges. Interest in smart contract security surged at the end of last year when an Anthropic study revealed that commercially available artificial intelligence (AI) agents had identified $4.6 million worth of smart contract exploits. Anthropic’s Claude Opus 4.5, Claude Sonnet 4.5, and OpenAI’s GPT-5 collectively developed these exploits when tested on smart contracts, according to a research paper by the AI company’s red team, which focuses on discovering code vulnerabilities before malicious actors can exploit them.
Smart contract vulnerabilities were identified as the largest attack vector for the cryptocurrency industry in 2025, with 56 cybersecurity incidents, according to SlowMist’s year-end report. These vulnerabilities accounted for 30.5% of all crypto exploits, while account compromises ranked second with 50 incidents. Meanwhile, crypto phishing scams emerged as the second-largest threat in 2025, costing investors $722 million across 248 incidents, as reported by blockchain security platform CertiK. These scams, which involve social engineering rather than code hacking, saw a 38% decrease in losses compared to the $1 billion stolen in 2024, indicating that investors are becoming more aware of such threats.
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