Science & Tech · Cybersecurity · 1 hr ago
Polymarket resumes trading after third-party security breach
Polymarket temporarily paused trading on its international platform on Thursday after a security incident involving a third-party provider.
The company said the provider was compromised, and trading resumed about an hour after the pause.
Security researchers traced about $2.5 million to a suspected attacker, while another estimate put the amount at about $2.7 million.
The incident affected Polymarket’s cryptocurrency-based international platform, not its separate US exchange.
Polymarket has not said how many traders were affected or confirmed how much was stolen.
It said all affected traders will be reimbursed.
The company referred the incident to UK law enforcement, while the provider warned its customers to remove its monitoring code from their websites.
Polymarket temporarily halted trading on its international platform after a compromised third-party service distributed malicious code that targeted users’ accounts.
The company said it fixed the issue, referred it to law enforcement and would reimburse affected traders.
Blockchain investigations traced about $2.5 million to a suspected attacker’s wallets, while one report estimated roughly 700 users were affected.
The incident did not affect Polymarket US, the company’s separate US platform.
- Who
- Polymarket users on its international platform were targeted. The company said a third-party provider was compromised.
- What
- Malicious code was used to drain cryptocurrency and other assets from some users’ accounts. Polymarket halted trading temporarily and said affected users would be reimbursed.
- When
- Thursday, October 29, 2026.
- Where
- Polymarket’s international platform, Polymarket.com. The compromised script was hosted on DebugBear infrastructure.
- Why
- A third-party service was compromised and its malicious script targeted users’ trading sessions and assets. The precise cause of the vendor breach was not stated.
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Blockchain records showed numerous transactions involving Polymarket’s token contract shortly before trading was suspended.
Polymarket placed its exchange in cancel-only mode and paused relayer actions while investigating.
Polymarket said it had fixed the issue and temporarily halted trading as a precaution.
Polymarket marked the incident resolved and said trading was back online.
- Estimated stolen assets
- Approximately $2.5 million to $2.7 million
- Users reportedly affected
- Around 700, according to Bubblemaps
- Compromised service
- DebugBear’s Real User Monitoring service
- Affected platform
- Polymarket’s international platform, Polymarket.com
- Unaffected platform
- Polymarket US
6 sources
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What people are saying
One of our third party providers was compromised, and we have referred this to relevant law enforcement
Anyone who has been impacted will be made whole.
We're impacted by an ongoing security incident
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We've identified & fixed an issue impacting our international platform, Polymarket.com. One of our 3rd party providers was compromised, and we have referred this to relevant law enforcement. Anyone who has been impacted will be made whole. Out of an abundance of caution, we
Trading is now fully back online. We’ll make this right and are fully reimbursing all affected traders.
Polymarket.com: The exchange is currently in cancel-only mode and relayer actions paused while we investigate an incident. We're aware of an outage and are looking into it.