CVE-1999-1087

7.5 HIGH 6% exploit odds Fix listed Other Browser & mail

What it is

Internet Explorer 4 treats a 32-bit number ("dotless IP address") in the a URL as the hostname instead of an IP address, which causes IE to apply Local Intranet Zone settings to the resulting web page, allowing remote malicious web servers to conduct unauthorized activities by using URLs that contain the dotless IP address for their server.

At a glance

Exploitability: Can be exploited over the network without logging in. Limited direct impact.
Exploit odds: 6.4% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1999-12-31 05:00 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-06-16 21:49 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 6.4% in the next 30 days (EPSS).
Severity: 7.5 HIGH (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 1999-12-31 05:00 UTC
Last modified: 2026-06-16 21:49 UTC
Exploit probability: 6.4% · EPSS, next 30 days
Record status: Modified

Affected

Microsoft Internet Explorer 4.0
Microsoft Internet Explorer 4.0.1

Attack profile CVSS 2.0 · 7.5

Attack vector: Network
Complexity: Low
Authentication: None
Confidentiality: Partial
Integrity: Partial
Availability: Partial

Raw vector

AV:N/AC:L/Au:N/C:P/I:P/A:P

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-1999-1087.md and follow it. Check whether this project is affected by CVE-1999-1087. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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Fix and advisories

References

NVD record · CVE.org record