GHSA-q4h9-46xg-m3x9

### 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.