Severity: Critical
CVSS Score: 10
### Impact Upgradeable contracts using `UUPSUpgradeable` may be vulnerable to an attack affecting uninitialized implementation contracts. We will update this advisory with more information soon. ### Patches A fix is included in version 4.3.2 of `@openzeppelin/contracts` and `@openzeppelin/contracts-upgradeable`. ### Workarounds Initialize implementation contracts using `UUPSUpgradeable` by invoking the initializer function (usually called `initialize`). An example is provided [in the forum](https://forum.openzeppelin.com/t/security-advisory-initialize-uups-implementation-contracts/15301). ### References A post-mortem will be published in a few days in the [OpenZeppelin Forum](https://forum.openzeppelin.com/). ### For more information If you have any questions or comments about this advisory, or need assistance executing the mitigation, email us at security@openzeppelin.com.