Polymarket Hacked: About $2.7 Million Stolen Through a Third-Party Provider

Prediction market Polymarket was hit by an exploit on October 29, 2026. Hackers drained an estimated $2.7 million from users of its international platform after one of Polymarket's third-party providers was compromised. Trading was paused, then resumed, and Polymarket has pledged to refund affected users in full. Here's what we know.

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What happened

• The cause: Polymarket said one of its third-party providers was compromised. CNBC reported, citing a person familiar with the matter, that it was tied to a hack of DebugBear, a website performance monitoring service, which confirmed a security incident.
• Losses: about $2.7 million, according to DeFiLlama's tracking. Polymarket hasn't confirmed a final total. One trader said they lost about $800,000.
• Who was affected: users of Polymarket's international platform. The company said its US platform was not compromised.
• Response: trading was halted and resumed at about 3 p.m. ET. Polymarket pledged full reimbursement but hasn't given a timeline, and referred the matter to UK law enforcement.

Not the first time this year

In June, a front-end attack on a different vendor drained roughly $3.1 million from about 11 wallets, and Polymarket refunded those users in full. Both incidents came through outside services, not Polymarket's own markets.

How to protect yourself

• Don't keep more on any platform than you're actively using. Move long-term crypto to a wallet you control.
• Use a hardware wallet for savings, and check every transaction on the device's own screen before you approve it.
• Revoke old token approvals you no longer need.
• Be suspicious of "refund" messages: scammers often pose as support after a hack. Only trust announcements on Polymarket's official channels.

More crypto security news: the Keystone hardware wallet breach and the Coinbase data exposure.

My take

Two hacks in one year, both through outside vendors, shows how much a modern app depends on services it doesn't control. Polymarket's full refunds are the right move, but the safest crypto is still the crypto you hold yourself. Do you keep funds on prediction markets?

This is news, not financial advice.