Hackers stole at least $2.6 million from hundreds of Polymarket accounts Thursday, Oct. 29, 2026, forcing the rapidly expanding prediction-market platform to temporarily suspend international trading after attackers exploited a compromised third-party software provider. Blockchain investigators estimated that approximately 700 users were affected, with malicious code reportedly allowing attackers to hijack authenticated trading sessions, liquidate positions and transfer cryptocurrency without authorization. The breach was linked to DebugBear, a website performance-monitoring service whose software was embedded in Polymarket’s platform. Trading resumed after approximately one hour, and Polymarket pledged to reimburse affected customers while referring the incident to British law enforcement. The attack follows previous security incidents and intensifies questions about cybersecurity standards, corporate accountability and the risks consumers face as cryptocurrency-based prediction markets attract increasing investment and regulatory scrutiny.
Key Takeaways
• Millions Stolen From Customer Accounts: Hackers reportedly drained at least $2.6 million from approximately 700 Polymarket accounts through malicious software capable of executing unauthorized cryptocurrency transactions.
• Third-Party Software Compromised: Investigators linked the breach to DebugBear, an outside website-monitoring provider, exposing the vulnerability of financial platforms that depend on external software services.
• Trading Restored, Accountability Questions Remain: Polymarket resumed operations after approximately one hour and promised full reimbursement, but the attack raises renewed concerns about cybersecurity safeguards and regulatory oversight.
In-Depth
Polymarket temporarily suspended trading Thursday after hackers exploited a third-party software vulnerability to steal at least $2.6 million from customer accounts, exposing another serious security weakness in the rapidly expanding prediction-market industry.
The October 29 attack reportedly affected approximately 700 accounts on Polymarket’s international platform. Investigators identified malicious JavaScript associated with DebugBear, a website performance-monitoring provider, that allegedly enabled attackers to hijack authenticated trading sessions, liquidate customer positions and transfer cryptocurrency into unauthorized wallets.
Blockchain researchers traced approximately $2.6 million in suspicious transactions. Some traders reported individual losses reaching hundreds of thousands of dollars, although Polymarket has not independently confirmed the total number of affected customers or the precise financial damage.
The company restricted trading to order cancellations while investigating the incident. After identifying and removing the compromised software, Polymarket restored normal operations approximately one hour later and promised to reimburse affected users.
British law enforcement authorities were notified because the implicated software provider operates in the United Kingdom.
The breach follows earlier security incidents involving compromised digital credentials and outside vendors, highlighting persistent vulnerabilities in cryptocurrency-based financial platforms.
For consumers, the implications extend beyond Polymarket. Financial technology companies increasingly rely on outside software providers, creating potential entry points for criminals even when their principal systems remain operational.
The incident also strengthens arguments for enforceable cybersecurity standards, transparent incident reporting and meaningful corporate accountability. Innovation and free-market competition remain essential, but neither eliminates a company’s responsibility to safeguard customer assets.
As prediction markets expand into elections, sports and financial events, public confidence will depend on demonstrable security protections rather than reimbursement promises issued after criminals have already struck.
Sources
• https://apnews.com/article/cd33bc1f9bf623103e1aeef3897846b5
• https://www.theblock.co/news/defi/2026-10-29-polymarket-exploit-2-5-million-cancel-only-mode-432158