Polymarket DebugBear Supply-Chain Frontend Attack
A compromise of monitoring vendor DebugBear injected malicious JavaScript into Polymarket's international frontend, draining about $2.7M in POL from roughly 700 wallets.
Vuln-watch · relayed from a public source; see Source & attribution below
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
OpenPGP-signed. The signed text of this advisory verifies against the 0xCERT key CCC7 D9EC 9415 723D.
Published 2026-10-29 · last updated 2026-10-30
curl -s https://www.0xcert.com/pgp.asc | gpg --import && curl -s https://www.0xcert.com/advisory/0xCERT-2026-0285/signed.txt | gpg --verify