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What happened during the third-party vendor hack that drained Polymarket users’ wallets on Thursday, October 29, including the nearly hour-long halt on its international exchange, trading’s reported resumption at 3 p.m. ET and the apparently unaffected U.S. platform; DebugBear’s
Polymarket halted trading on its international exchange for nearly an hour on Thursday, October 29, 2026, after a compromised third-party service delivered wallet-draining code; it subsequently said the issue was fixed and promised full reimbursement to affected traders. [10][13][16] Reports traced Polymarket halted...
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Key takeaways
- Polymarket halted trading on its international exchange for nearly an hour on Thursday, October 29, 2026, after a compromised third-party service delivered wallet-draining code; it subsequently said the issue was fixed and promised full reimbursement to affected traders. [10][13][16] Reports traced
- Polymarket halted trading on its international exchange for nearly an hour on Thursday, October 29, 2026, after a compromised third-party service delivered wallet-draining code; it subsequently said the issue was fixed and promised full reimbursement to affected traders. [10][13]
- ## What happened
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openai.comCreate a landscape editorial hero image for this Studio Global article: What happened during the third party vendor hack that drained Polymarket users’ wallets on Thursday, October 29, including the nearly hour l. Article summary: Polymarket halted trading on its international exchange for nearly an hour on Thursday, October 29, 2026, after a compromised third party service delivered wallet draining code; it subsequently said the issue was fixed a. Topic tags: general web, prompt engineering, ai, workflow, code. Style: premium digital editorial illustration, source-backed research mood, clean composition, high detail, modern web publication hero. Use reference image context only for broad subject, composition, and topical grounding; do not copy the exact image. Avoid: logos, brand marks, copyrighted characters, real person likenesses, fake screenshots, UI text, readable text, watermarks,
Polymarket halted trading on its international exchange for nearly an hour on Thursday, October 29, 2026, after a compromised third-party service delivered wallet-draining code; it subsequently said the issue was fixed and promised full reimbursement to affected traders. 10
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16 Reports traced the attack to a DebugBear monitoring script embedded in Polymarket’s website, while blockchain analysis identified roughly $2.65 million in POL at a suspected attacker address.
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What happened
- Attack route: Analysts reportedly traced the compromise to DebugBear’s Real User Monitoring script, which Polymarket loaded on its frontend.
7 The available excerpts establish a malicious third-party script, but provide insufficient evidence to independently confirm DebugBear’s acknowledgment, the underlying security flaw, or the precise sequence of stealing browser-held credentials, selling positions at steep discounts and transferring the proceeds.
- Trading restrictions: Polymarket entered cancel-only mode—allowing existing orders to be canceled but blocking new buy and sell orders—and paused its relayer.
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14 Trading reportedly reopened around 3 p.m. ET, following approximately an hour’s interruption; CNBC reported that the U.S. platform appeared unaffected.
16 Insufficient evidence in the available excerpts establishes the exact relayer restrictions on token transfers and spending approvals.
Losses and response
- Trader claims: One trader reported losing $800,000 and said a friend lost another $600,000; these are reported claims, not independently verified losses in the available evidence.
- Blockchain trail: Reports citing Arkham showed the suspected attacker converting USDC.e and USDC into POL, holding approximately $2.65 million worth at one point, and subsequently transferring funds out.
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- Backup recipient: The technical-analysis result identified a hardcoded fallback recipient in the retrieved script; a supplied screenshot showed about $2.18 million in POL at that address at a different observation point.
6 The excerpts do not conclusively establish the requested attribution of that finding to Hudson Rock.
- Remediation: Polymarket said it had fixed the issue, referred the matter to law enforcement—with CNBC reporting a U.K. referral—and pledged to reimburse all affected traders.
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Context and evidence limits
- Election scrutiny: Separately, Polymarket was investigating suspicious, well-timed and profitable trades surrounding Israel’s election, including bets from hundreds of newly created accounts shortly before polls closed.
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3 The available evidence does not establish a connection between those trades and the hack.
- Unverified background: Insufficient evidence was retrieved to confirm June’s approximately $3 million vendor-related theft from fewer than 15 accounts and subsequent refunds, the characterization of October’s attack as the year’s third security incident, September’s $21 billion valuation, the expected November 3 midterm trading surge, or investigations specifically involving midterm bets. Those details should not be treated as verified from this source set.
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Polymarket halted trading on its international exchange for nearly an hour on Thursday, October 29, 2026, after a compromised third-party service delivered wallet-draining code; it subsequently said the issue was fixed and promised full reimbursement to affected traders. [10][13][16] Reports traced
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Polymarket halted trading on its international exchange for nearly an hour on Thursday, October 29, 2026, after a compromised third-party service delivered wallet-draining code; it subsequently said the issue was fixed and promised full reimbursement to affected traders. [10][13][16] Reports traced Polymarket halted trading on its international exchange for nearly an hour on Thursday, October 29, 2026, after a compromised third-party service delivered wallet-draining code; it subsequently said the issue was fixed and promised full reimbursement to affected traders. [10][13]
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## What happened
Sources
ground.newsSome Polymarket Users Report Losing Funds After Security Breach