Prediction Market Giant Polymarket Loses $3.1 Million in Cyberattack

Polymarket has confirmed a $3.1 million cyberattack, raising questions about how secure prediction markets really are, especially now that they are infiltrating iGaming.

Polymarket suffered a $3.1 million cyberattack after hackers compromised a third-party vendor, injecting malicious code into the platform's frontend.

The breach raises questions about how secure prediction markets really are, just as the sector pushes for mainstream growth and starts its run for online casinos.

The $3.1 million attack

Polymarket was hit on 25 June 2026. The attack occurred through a third-party vendor, which allowed the hackers to access the platform's own system.

However, the company hasn't provided information on which vendor was compromised or how many individuals were affected, or who orchestrated the attack. PeckShield, a Blockchain monitoring and security firm, estimates that 11 users lost a combined $3.1 million.

Polymarkets response & user reports

Polymarket confirmed that they have identified the compromised vendor, contained the breach, and removed the affected dependency. The platform also made it clear that every affected user will be contacted and refunded in full.

One user impacted by the attack claims they recently bought a VPS from Xorek Cloud and stored their private key on it, and, to their knowledge, this is the only possible security risk they can identify. However, nothing has been officially confirmed.

The backlash

Polymarket users lose millions after cyberattack — How did Polymarket users react to the cyberattack?

Since the attack was made public, Polymarket has been met with a lot of online criticism. Several users claim they'd already warned the platform of a breach and the vulnerabilities they'd found themselves.

Despite this outcry, Polymarket has not given a clear timeline for when funds will be returned to users. But they stated that the refunds are in process.

Prediction market oversight

CasinoWow recently covered how prediction markets are coming for iGaming, especially with Gen Z's demand for fast, real-money engagement.

The appeal is structural. They are the next big thing after the major roar that crypto casinos caused. Prediction markets come with many benefits, such as operating on dynamic, crowd-driven probabilities instead of fixed odds.

They allow users to trade positions before the outcome is known. Not to mention that the constant updates give users a social-media-like engagement feel, focused on real-world events.

Revenue is generated through transaction fees rather than the house edge, as is the case with traditional online casinos. That's already pulled in major operators like DraftKings, which has launched its own prediction market exchange.

Many casinos have also infiltrated prediction markets or similar features into their offerings. Some of the first to lead are BiggerZ, Rooster.bet and N1 Casino.

BiggerZ Casino Learn more

Rooster.bet Casino Learn more

N1 Casino Learn more

The tradeoff is exposure. Prediction markets, as a separate platform, rely on third-party integrations and decentralised infrastructure. And as Polymarket's breach indicates, this is enough of a vulnerability.

Implications for players and operators

Prediction markets aren't going away. They are already embraced by younger players, and traditional sportsbooks and casinos are already borrowing popular mechanics.

The upside for cautious and secure operators is that they can gain a competitive edge and draw in more users, as platforms that can show stronger cybersecurity and responsible gambling measures are more important now in the decision-making process.

Responsible Gambling & Play Safe — Gamble RESPONSIBLY. At CasinoWow, we're dedicated to responsible gambling and we provide you with many resources to help you play safe.

All in all, a $3.1 million breach is a wake-up call and a reminder to treat prediction markets with the same caution as anywhere else holding your money.

Platforms may be becoming more eager to attract attention, but they need to provide suitable security measures as well. Players, on the other hand, need to check what's protecting their funds before trusting the platform with any of them.

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By Deni

Verified Casino Expert

Expertise: Casino Content Writing, Journalism & (PR), Gambling Regulations, Dutch & German Gambling Markets

Hi, I'm Deni! I'm a research obsessive with a passion for gambling regulations, market trends, and casino news. I dig deep into every topic I cover - so every article, review, or guide I write is built on solid research and real detail.

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Last updated: July 10, 2026

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Prediction market giant Polymarket loses $3.1 million in cyberattack

The $3.1 million attack

Polymarkets response & user reports

The backlash

Prediction market oversight