CVE-1999-1591

highpriority · track · 34EPSS 0.113 · 96 %ileEUUS

grimoire priorityP1 · Urgent

Exploitable?

—

no known exploitation

Likely / severe?

11.3% (96th) EPSS

CVSS 7.5 · high

Is it mine?

3 products

Check your exposure

Who says so?

2 sources

enisa_euvd · nvd

EPSS · scored 2026-10-27

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.

cvss

Technical severity, 0–10. One row per scoring source.

7.5

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 6.4–7.5

v2.07.5highAV:N/AC:L/Au:N/C:P/I:P/A:Pprimary · NVD / NIST USexploitability 10 · impact 6.4

v2.06.4mediumAV:N/AC:L/Au:N/C:P/I:P/A:P/E:Usecondary · CVSS-BT (t0sche)

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-287USLLM-inferred

affected products (3)

Products and version ranges known to be affected.

n/a n/a≤ n/aenisa_euvdEU
microsoft internet information server= 4.0nvdUScpe:2.3:a:microsoft:internet_information_server:*:*:*:*:*:*:*:*
microsoft visual interdev= 6.0nvdUScpe:2.3:a:microsoft:visual_interdev:*:*:*:*:*:*:*:*

also known as (2)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

enisa_euvd nvd NVD CVE.org MITRE

published 1999-12-31modified 2026-06-16

references (6)

External citations — patches, advisories, analysis.

scry

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