The registry entry for the Windows Shell executable (Explorer.exe) in Windows NT and Windows 2000 uses a relative path name, which allows local users to execute arbitrary commands by inserting a Trojan Horse named Explorer.exe into the %Systemdrive% directory, aka the "Relative Shell Path" vulnerability.
https://exchange.xforce.ibmcloud.com/vulnerabilities/5040
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2000/ms00-052