GHSA-9c22-pwxw-p6hx

Description

### Impact Initializer functions that are invoked separate from contract creation (the most prominent example being minimal proxies) may be reentered if they make an untrusted non-view external call. Once an initializer has finished running it can never be re-executed. However, an exception put in place to support multiple inheritance made reentrancy possible in the scenario described above, breaking the expectation that there is a single execution. Note that upgradeable proxies are commonly initialized together with contract creation, where reentrancy is not feasible, so the impact of this issue is believed to be minor. ### Patches A fix is included in the version v4.4.1 of `@openzeppelin/contracts` and `@openzeppelin/contracts-upgradeable`. ### Workarounds Avoid untrusted external calls during initialization. ### References https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3006 ### Credits This issue was identified and reported by @chaitinblockchain through [our bug bounty on Immunefi](https://immunefi.com/bounty/openzeppelin/). ### 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.