Polymarket Hack News: Attack Hit UMA Adapter Contracts for $520k

Polymarket Hack Targets UMA Contracts on Polygon: Are User Funds Safe?

Polymarket, the world’s largest prediction market, is dealing with a major security scare on the Polygon network today. On May 22, 2026, famous on-chain investigator ZachXBT sounded the alarm about a suspected Polymarket Hack draining funds from internal contracts. 

Source: Official Telegram Account

An automated script systematically pulled batches of tokens out of the protocol every few seconds. Have you checked if your prediction market balances are safe after this security breach?

Automated Script Drains Funds From Internal Wallets 

The incident targeted the platform's UMA CTF Adapter setup, which connects the prediction market to its data oracle. Blockchain data showed the attacker stealing roughly 5,000 POL tokens every 20 to 30 seconds. This mechanical pace proved that the thief used an automated script to empty the wallets quickly.

Initial alerts estimated the damage at $520k, though later reports indicated the total losses climbed past $660k. The primary contracts hit in the attack were: 

• 0x871D7c0f9E19001fC01E04e6cdFa7fA20f929082

• 0x91430CaD2d3975766499717fA0D66A78D814E5c5 

On-chain records show the thief moved the stolen loot to a single address, 0x8F98075db5d6C620e8D420A8c516E2F2059d9B91, before scattering it across other wallets.

Polymarket Clarifies The Security Breach Mechanics 

The engineering team moved fast to explain exactly how the thief bypassed their defenses. Vice President of Engineering Josh Stevens and protocol leaders confirmed that the core trading platform remains completely unharmed. This security failure was not an exploit of their smart contract code or core trading systems.

Instead, the team traced the issue back to a compromised old private key. This legacy wallet was used for backend internal chores like managing rewards and distribution. Because the key leaked, the hacker gained direct access to the funds stored in those specific admin contracts.

User Funds Safety? The Oracle Connection Risks 

The UMA CTF Adapter usually serves as a vital bridge for the prediction platform. It links UMA's Optimistic Oracle to Polymarket's Conditional Tokens Framework to resolve betting outcomes on the blockchain. Thankfully, this specific leak only touched the reward functions rather than the primary market resolution contracts.

Source: Product Lead at Polymarket

The executive team assured the community that user deposits, active trading positions, and market settlements face zero risk. While the platform core is fine, the news caused the UMA token price to dip 3.3% during intraday trading. The POL token price remained relatively steady despite the chaos.

Ongoing Infrastructure Hurdles For The Prediction Giant

This security slip adds to a list of infrastructure headaches the betting giant has faced recently. The platform dealt with severe UMA governance disputes in 2025, where wealthy whales manipulated market resolutions. They also fought third-party wallet vulnerabilities late last year and a major data scraping incident in April 2026.

As the platform tries to expand globally and secure official licenses in places like Japan, admin key management is more vital than ever. For now, users do not need to panic or close their positions. The team is still tracking the stolen funds and promises to share deep security upgrades soon.

Note: This article is for information purposes only. All the information and facts are based on market present data. The article itself does not claim anything.