ShiftController Employee Shift Scheduling Plugin Vulnerable to PHP Object Injection via Deserialization

Summary

The ShiftController Employee Shift Scheduling plugin is vulnerable to PHP Object Injection via deserialization of untrusted input via the `hc3_session`-cookie in versions up to, and including, 4.9.57. This makes it possible for an authenticated attacker with contributor access-level or above to inject a PHP Object. No POP chain is present in the vulnerable plugin. If a POP chain is present via an additional plugin or theme installed on the target system, it could allow the attacker to delete arbitrary files, retrieve sensitive data, or execute code.