Security incident · 2021-06-20
Polydex
According to the public DefiLlama incident dataset, Polydex (Polygon) suffered a security incident on 2021-06-20, with about $500K reported lost.
| Date | 2021-06-20 |
|---|---|
| Reported loss | $500K |
| Chain | Polygon |
| Target type | DeFi Protocol |
| Technique class | Reentrancy |
| Technique | Reentrancy |
| Bridge incident | No |
| Within 2021 | #99 by loss that year, 0.0% of all reported losses that year |
How this kind of attack works
The contract sent funds before updating balances, and the attacker re-entered during the transfer to withdraw repeatedly.
Would a pre-payment check have helped
Reentrancy is a classic contract bug, unrelated to the counterparty; code audits address it.
Other incidents with the same technique
- Rari Capital2022-05-01 · $80.0M
- Curve DEX2023-07-30 · $61.7M
- The DAO2016-06-17 · $60.0M
- GMX V1 Perps2025-07-09 · $42.0M
- Grim Finance2021-12-18 · $30.0M
- Penpie2024-09-03 · $27.0M