Attackers reportedly compromised a third-party website monitoring service used by Polymarket, allowing malicious JavaScript to execute on its international trading platform. The script hijacked authenticated trading sessions to sell prediction-market positions and transfer assets to attacker-controlled wallets. Polymarket temporarily suspended trading, removed the affected integration, and committed to reimbursing impacted users

Polymarket’s international platform (Polymarket.com) suffered a security incident after a third-party provider (DebugBear, a website performance monitoring tool) was compromised. Malicious JavaScript drained funds from some users’ accounts (approximately $2.65–2.7 million). Trading was paused for about an hour, then resumed. Polymarket promised to fully reimburse all affected traders and referred the matter to UK law enforcement.