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Third-Party Breach at Polymarket Leads to $2.94M Crypto Theft

Securityaffairs.Co •Pierluigi Paganini • June 26, 2026

Polymarket confirmed hackers stole funds from some users after attackers injected malicious code through a compromised third-party vendor. Polymarket confirmed that a security breach at a third-party vendor allowed attackers to inject malicious code into its website, leading to the theft of funds from an undisclosed number of users. The company said it has contained […]

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This article is one source in a clustered incident — the cluster page carries the summary, timeline and every other outlet covering it.

Polymarket Suffers $3M Theft from Supply-Chain Attack via Third-Party Vendor On June 25, 2026, Polymarket confirmed a security breach that led to the theft of approximately $3 million from fewer than 15 user accounts. The attack was executed through a compromised third-party vendor, which allowed hackers to inject malicious code into Polymarket's website frontend. The stolen funds primarily consisted of Polymarket's pUSD stablecoin, which were quickly converted to Ethereum (ETH) to obscure the trail. Blockchain analysts reported that over 11 wallets were affected, with the attackers consolidating the stolen assets into a single address. Polymarket has assured all impacted users that they will be fully reimbursed and has removed the compromised vendor dependency. This incident follows a previous breach in May 2026, where the platform lost approximately $700,000 due to a separate attack targeting employee wallets. The company is now facing scrutiny regarding its vendor vetting processes and security measures. 45 sources 65

Third-Party Breach at Polymarket Leads to $2.94M Crypto Theft

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