The recommendation is to use the latest version available.
| Version | Supported |
|---|---|
| 4.x | ✅✅ |
| 3.4 | ✅ |
| 2.5 | ✅ |
| < 2.0 | ❌ |
Note that the Solidity language itself only guarantees security updates for the latest release.
Please report any security issues you find to security@openzeppelin.org.
Critical bug fixes will be backported to past major releases.