Provide references for CVE-2021-39168.
Where can I find more information about CVE-2021-39168?
References are available at: https://github.com/OpenZeppelin/openzeppelin-contracts-upgradeable/security/advisories/GHSA-vrw4-w73r-6mm8, https://github.com/OpenZeppelin/openzeppelin-contracts/commit/cec4f2ef57495d8b1742d62846da212515d99dd5, https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/CHANGELOG.md#431.