FrontPage Server Extensions (FPSE) in IIS 4.0 and 5.0 allows remote attackers to cause a denial of service via a malformed form, aka the "Malformed Web Form Submission" vulnerability.
https://exchange.xforce.ibmcloud.com/vulnerabilities/5823
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2000/ms00-100