Traders using the international platform of prediction market Polymarket saw unauthorized withdrawals from their wallets on Thursday afternoon. Users initially reported on social media that funds were being moved without approval. The disruption prompted the decentralized finance platform to halt international trading while addressing the problem. Trading resumed at 3 p.m. ET after the team resolved the issue on its end, while its domestic platform remained entirely uncompromised.

The security incident originated from a breach at DebugBear, an external website performance monitoring tool based in the United Kingdom. DebugBear acknowledged on social media that it suffered a security issue on Thursday. Because the service provider is incorporated in Britain, the matter was referred to law enforcement authorities in the United Kingdom. Polymarket confirmed that the vulnerability stemmed from this external vendor rather than an exploit of its own platform operations.

Public blockchain records evaluated by analytics specialists revealed that a single account managed to withdraw at least 2.7 million dollars across 710 separate user wallets during the incident. The international prediction market operates on the Polygon blockchain without regulatory supervision in the United States. Observers highlighted the breach as an unusual and significant event for the venue, particularly given the operational sensitivity surrounding its decentralized finance markets.

To address user losses, the platform pledged to reimburse every affected customer. According to updates shared in a chatroom on Discord, wallets with less than 10,000 dollars taken will have their balances restored by October 30. Account holders who lost larger amounts exceeding that threshold must sign a formal release form before obtaining restitution. While the total number of compromised accounts has not been officially confirmed, the remediation framework sets explicit recovery conditions.

The timing of the disruption is notable as it arrived shortly before the United States midterm elections on November 3. Both the international service and the domestic exchange had anticipated heightened trading volumes in connection with the voting cycle. A similar security issue previously occurred in June, when another third-party vendor was compromised, leading to comparable platform refunds for impacted participants. The recurrence underscores operational challenges with external tools.

External software dependencies continue to introduce security challenges for platforms operating across distributed networks. While core smart contract ledgers on the Polygon network remained intact, peripheral monitoring integrations created an unintended path for unauthorized balance withdrawals. Market participants are left navigating self-administered reimbursement procedures while law enforcement reviews the vendor breach, highlighting ongoing operational dependencies in the sector.