Polymarket-linked adapter drained for at least $520K in suspected exploitLatest NewsPublishedMay 22, 2026ZachXBT said that Polymarket’s smart contract was drained for at least $520,000, pointing to an alleged attacker address that received hundreds of small transactions from the adapter contract.A Polymarket-linked UMA Conditional Tokens Framework (CTF) Adapter contract on Polygon may have been exploited for at least $520,000, according to blockchain investigator ZachXBT.ZachXBT said in a Friday Telegram post that the suspected exploiter had drained funds from addresses allegedly connected to the adapter contract. Cointelegraph could not immediately verify whether Polymarket user funds, active markets or withdrawals were affected.The UMA CTF adapter is an oracle contract used to help resolve Polymarket prediction markets through UMA’s Optimistic Oracle.Polymarket is the world's second-largest prediction market with $3.7 billion in monthly trading volume, according to DefiLlama. Polyscan data reviewed by Cointelegraph showed more than 100 recent small transfers into the alleged attacker wallet. Most were worth up to 5,000 Polygon (POL) tokens.Address of the alleged Polymarket adapter contract attacker. Source: PolygonscanExploit losses climb past $600,000Multiple blockchain data platforms reported similar onchain activity tied to the suspected exploit.Blockchain data visualization platform Bubblemaps said in a Friday X post that the attacker continues to remove about 5,000 POL tokens every 30 seconds, amassing about $600,000 in stolen funds so far.Source: BubblemapsBlockchain data platform Lookonchain estimated that about $660,000 was drained from the Polymarket-linked contract as of 9:01 am UTC on Friday.Related: Crypto VC funding plunges to $659M in April, hits near two-year lowPolymarket integrated UMA's optimistic oracle solution on Feb. 3, 2022, enabling automated and decentralized resolution for its prediction market contracts.Cointelegraph contacted Polymarket and UMA for comment but had not received a response by publication.Magazine: The legal battle over who can claim DeFi’s stolen millions Cointelegraph is committed to independent, transparent journalism. This news article is produced in accordance with Cointelegraph’s Editorial Policy and aims to provide accurate and timely information. Readers are encouraged to verify information independently.