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CVE-1999-1591

7.5 · HIGH

Microsoft Internet Information Services (IIS) server 4.0 SP4, without certain hotfixes released for SP4, does not require authentication credentials under certain conditions, which allows remote at…

Published Dec 31, 1999microsoftEPSS 11.27%

Overview

CVE-1999-1591 is a high-severity vulnerability affecting microsoft internet_information_server. It was published on December 31, 1999 and has a CVSS 2.0 base score of 7.5 (HIGH).

This vulnerability has a CVSS 2.0 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

Microsoft Internet Information Services (IIS) server 4.0 SP4, without certain hotfixes released for SP4, does not require authentication credentials under certain conditions, which allows remote attackers to bypass authentication requirements, as demonstrated by connecting via Microsoft Visual InterDev 6.0.

Remediation

Check the references section for vendor advisories and patches from microsoft. Update internet_information_server to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

Affected products

VendorProductVersionsStatus

Frequently asked questions

What is CVE-1999-1591?

CVE-1999-1591 is a high-severity vulnerability affecting microsoft internet_information_server. It was published on December 31, 1999 and has a CVSS 2.0 base score of 7.5 (HIGH).

How severe is CVE-1999-1591?

This vulnerability has a CVSS 2.0 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-1999-1591?

Check the references section for vendor advisories and patches from microsoft. Update internet_information_server to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-1999-1591?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-1999-1591 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.