How severe is CVE-2001-0004?

CVE-2001-0004 has a CVSS 2.0 base score of 5.0, rated medium severity.

Is CVE-2001-0004 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 28% (98th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2001-0004?

CVE-2001-0004 primarily affects Microsoft Internet Information Server. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2001-0004?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2001-0004 published?

CVE-2001-0004 was published on 2001-02-12 and last updated on 2026-06-16.

CVE-2001-0004

CVE-2001-0004 is a medium-severity vulnerability in Microsoft Internet Information Server with a CVSS 2.0 base score of 5.0. Its EPSS exploit-prediction score of 28% places it in the 98th percentile, indicating an elevated likelihood of exploitation.

Key facts

Severity: Medium (CVSS 2.0 base score 5.0)
EPSS exploit prediction: 28% (98th percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Microsoft Internet Information Server
Published: 2001-02-12
Last modified: 2026-06-16

Description

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.

Frequently asked questions

What is CVE-2001-0004?: 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.
How severe is CVE-2001-0004?: CVE-2001-0004 has a CVSS 2.0 base score of 5.0, rated medium severity.
Is CVE-2001-0004 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 28% (98th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2001-0004?: CVE-2001-0004 primarily affects Microsoft Internet Information Server. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2001-0004?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2001-0004 published?: CVE-2001-0004 was published on 2001-02-12 and last updated on 2026-06-16.

References

Affected products (2)

cpe:2.3:a:microsoft:internet_information_server:4.0:*:*:*:*:*:*:*
cpe:2.3:a:microsoft:internet_information_services:5.0:*:*:*:*:*:*:*

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