CVE-2023-34234: Generation of Predictable Numbers or Identifiers

OpenZeppelin Contracts is a library for smart contract development. 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. This problem has been patched in 4.9.1 by introducing opt-in frontrunning protection. Users are advised to upgrade. Users unable to upgrade may submit the proposal creation transaction to an endpoint with frontrunning protection as a workaround.