| Package | Affected versions | Patched versions |
|---|---|---|
| contracts | ≥ 4.3.0, < 4.9.1 | 4.9.1 |
| contracts upgradeable | ≥ 4.3.0, < 4.9.1 | 4.9.1 |
| @openzeppelin/contracts | ≥ 4.3.0, < 4.9.1 | 4.9.1 |
| @openzeppelin/contracts-upgradeable | ≥ 4.3.0, < 4.9.1 | 4.9.1 |
By frontrunning the creation of a proposal, an attacker can become the proposer and gain the ability to cancel it. The attacker can do this repeatedly to try to prevent a proposal from being proposed at all.
This impacts the Governor contract in v4.9.0 only, and the GovernorCompatibilityBravo contract since v4.3.0.
The problem has been patched in 4.9.1 by introducing opt-in frontrunning protection.
Submit the proposal creation transaction to an endpoint with frontrunning protection.
Reported by Lior Abadi and Joaquin Pereyra from Coinspect.
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