Polymarket has resumed trading operations after addressing a security incident related to a third-party service provider. The platform had suspended its international trading services on October 29 due to reports of unauthorized withdrawals affecting some user accounts. This breach led Polymarket to confirm the incident and offer reassurances that all impacted users would be compensated for their losses.
The United Kingdom authorities have initiated an investigation into the breach, although the company has not disclosed the total financial impact of the incident.
Reports from users indicated that funds were withdrawn from their accounts without consent. According to blockchain analytics firm Bubblemaps, around 700 users appear to have been affected, with cumulative losses estimated at approximately $2.7 million.
The compromised vendor responsible for the breach has been identified as DebugBear, a service that monitors website performance. DebugBear acknowledged the security breach and has advised its clients to remove code linked to their Real User Monitoring service from their websites. Details about how the breach occurred and the full extent of the damage are still unclear as investigators continue their work.
Trading activities on Polymarket had been placed on hold while the company conducted its investigation. Trading recommenced on Thursday after the issues were resolved. Although affected users will receive compensation, Polymarket has not shared specific figures regarding the number of compromised accounts or the total compensation required. It is important to note that this incident did not impact Polymarket’s dedicated US platform.
This isn’t the first security breach Polymarket has faced. A prior incident occurred in June 2026, when hackers exploited an external service provider’s vulnerability, resulting in approximately $3 million being siphoned from users' accounts. The latest breach serves as a cautionary tale regarding the risks associated with third-party software. Despite Polymarket's commitment to covering traders' losses, the ongoing investigation into this recent breach continues.
