GHSA-w6jr-wj64-mc9x

### Impact
Deserialization of Untrusted Data was found in the `old()` function in CodeIgniter4.
Remote attackers may inject auto-loadable arbitrary objects with this vulnerability,
and possibly execute existing PHP code on the server.
We are aware of a working exploit, which can lead to SQL injection.

### Patches
Upgrade to v4.1.6 or later.

### Workarounds
Do not use:
- `old()` and form_helper
- `RedirectResponse::withInput()` and `redirect()->withInput()`

### References
- [PHP Object Injection | OWASP](https://owasp.org/www-community/vulnerabilities/PHP_Object_Injection)

### For more information
If you have any questions or comments about this advisory:
* Open an issue in [codeigniter4/CodeIgniter4](https://github.com/codeigniter4/CodeIgniter4/issues)
* Email us at [SECURITY.md](https://github.com/codeigniter4/CodeIgniter4/blob/develop/SECURITY.md)