Polymarket 2026 Supply Chain Attack via Third-Party Vendor

Polymarket, a cryptocurrency-based prediction market platform, suffered a supply chain attack after a third-party frontend vendor was breached. The incident was confirmed in a threat intelligence report published on 29th June 2026. No specific record count or user population impact was disclosed, but the attack involved malicious JavaScript being injected into Polymarket's website.

The attack chain began with a compromise of a third-party frontend vendor, which allowed attackers to inject malicious JavaScript into Polymarket's website. This script tricked users into approving fraudulent transactions, effectively enabling unauthorized actions on the platform. The exact data compromised is not detailed, but the attack targeted user approvals, likely leading to financial losses. No threat actor was attributed in the report.

Post-incident details are not provided in the article. There is no mention of regulatory involvement, litigation, ransom payment, or breach notification status. The report focuses solely on the attack vector and its confirmation.