CVE-2001-0004: Microsoft Internet Information Server

Medium severity, CVSS 5.0. EPSS: 28.2% chance of exploitation in the next 30 days.

IIS 5.0 and 4.0 allows remote attackers to read the source code for executable web server programs by appending "%3F+.htr" to the requested URL, which causes the files to be parsed by the .HTR ISAPI extension, aka a variant of the "File Fragment Reading via .HTR" vulnerability.

Affected products

• Microsoft Internet Information Server: version 4.0 only
• Microsoft Internet Information Services: version 5.0 only

Published 2001-02-12. Last modified 2026-06-16.