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0xCERT Security Advisory 0xCERT-2026-0285
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Advisory-ID:  0xCERT-2026-0285
Severity:     High
Published:    2026-10-29T00:00:00.000Z
Updated:      2026-10-30T07:23:32.748Z
Chains:       Polygon
URL:          https://www.0xcert.com/advisory/0xCERT-2026-0285

Title: Polymarket DebugBear Supply-Chain Frontend Attack

Summary
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A compromise of monitoring vendor DebugBear injected malicious JavaScript into Polymarket's international frontend, draining about $2.7M in POL from roughly 700 wallets.

Details
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Summary
A compromise of monitoring vendor DebugBear injected malicious JavaScript into Polymarket's international frontend, draining about $2.7M in POL from roughly 700 wallets.

Incident
- - Victim: Polymarket
- - Date (UTC): 2026-10-29
- - Estimated loss: $2.7M
- - Chain(s): Polygon
- - Attack type: front-end compromise
- - Funds status: stolen

Recommended actions
- - Revoke token approvals granted to Polymarket contracts until the project confirms they are safe
- - Integrators: pause or delist affected assets and monitor for attacker fund movements
- - Beware of follow-on phishing: ignore unofficial "refund", "recovery", or "claim" links and DMs; use the project's verified channels only

Source & attribution
Full analysis on Blockchain Breaches, 0xCERT's incident archive: https://www.blockchainbreaches.com/en/breaches/polymarket-october-2026. Primary sources: https://cryptoadventure.com/polymarket-hack-drains-2-7m-from-737-wallets/ ; https://rg.org/news/prediction-markets/polymarket-third-party-provider-breach-user-funds-drained.

References
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- - https://www.blockchainbreaches.com/en/breaches/polymarket-october-2026
- - https://cryptoadventure.com/polymarket-hack-drains-2-7m-from-737-wallets/
- - https://rg.org/news/prediction-markets/polymarket-third-party-provider-breach-user-funds-drained

Verify with the 0xCERT OpenPGP key: https://www.0xcert.com/pgp.asc
Fingerprint: 5F94 3ED1 1E50 CF31 2128  C493 CCC7 D9EC 9415 723D

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