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CVE-1999-1591: Microsoft Internet Information Services (IIS) server 4.0 SP4, without certain hotfixes released for SP4, does not requir

UNKNOWN

Published n/a Updated 2026-08-21T04:30:53.669Z

Summary

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.

Why It Matters

UNKNOWN severity with CVSS n/a.

Risks left unpatched can lead to remote code execution, data exposure or lateral movement — verify exposure against the affected software below.

Current Status

  • Vulnerability status: Not listed in CISA KEV
  • Last intelligence update: 2026-08-21 · source: NVD

Entity Activity Timeline

  1. 2026-08-21 — Intelligence record updated（NVD sync）

No recorded activity beyond NVD publication and sync updates.

Severity

UNKNOWN

Source Attribution

Source: NVD · Updated: 2026-08-21T04:30:53.669Z · Confidence: high

Impact

Based on CVSS vector: n/a — assess confidentiality, integrity, and availability impact via the official vector documentation.

Affected Software

Fix

Upgrade affected software to the fixed version identified above. Apply vendor patches and monitor advisories before exposed systems go unpatched.

Sources & Evidence

6 reference(s) · attribution: NVD

Related Intelligence

Curated links only — no machine-generated relationships.

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  1. Question — what do you need to know about CVE-1999-1591: Microsoft Internet Information Services (IIS) server 4.0 SP4, without certain hotfixes released for SP4, does not requir?
  2. Evidence — assertions mapped to verifiable references.
  3. Timeline — events in chronological order.
  4. Related Entities — CVE, threat actor, campaign, malware links.
  5. Sources — NVD, CISA KEV, MITRE ATT&CK, vendor advisories.
  6. Notes — your own observations and working hypotheses.

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