# CVE-1999-0511: Generic Operating System IP forwarding enabled on non-router host

Source: https://junglewise.ai/threats/cve-1999-0511-generic-operating-system-ip-forwarding-enabled-on-non-router-host  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 1997-01-01. Updated: 2026-05-10  
License: CC BY 4.0 with a link back

CVE-1999-0511 · Severity: high · CVSS 7.5 · Published 1997-01-01

A configuration issue exists where standard computers or servers are inadvertently acting as network routers. This allows unauthorized network traffic to pass through the system, potentially bypassing security perimeters or exposing internal network segments. An attacker could use this to reach protected systems that should not be accessible from their location.

Technologies: [Microsoft Windows 2000](https://junglewise.ai/threats/technologies/windows-2000), [Microsoft Windows Nt](https://junglewise.ai/threats/technologies/windows-nt). Vendors: [Microsoft](https://junglewise.ai/threats/vendors/microsoft).

## Quick answers

**Is CVE-1999-0511 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-1999-0511 being exploited in the wild.

**How severe is CVE-1999-0511?** High severity, with a CVSS score of 7.5, published 1 January 1997.

**Which products and versions are affected?** Microsoft Windows 2000, Microsoft Windows Nt. The advisory does not name versions.

**Is there a fix for CVE-1999-0511?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-1999-0511 attacked?** It is attacked over the network, in an operating system.

**Am I affected by CVE-1999-0511?** Check whether you run Microsoft Windows 2000 or Microsoft Windows Nt. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The system is configured with IP forwarding enabled (e.g., net.ipv4.ip_forward = 1 on Linux), despite not being a dedicated networking device. This configuration allows the host to route packets between different network interfaces or subnets. A remote attacker can leverage this to bypass network access control lists (ACLs) or reach internal network segments that are otherwise isolated. This is a common misconfiguration in multi-homed systems that can lead to unauthorized network traversal. Remediation involves disabling IP forwarding in the operating system kernel settings if routing capabilities are not required for the business function of the host.

## Affected products

- Microsoft Windows 2000
- Microsoft Windows Nt

## Timeline

- 1997-01-01: disclosed: NVD Published Date

## References

- [https://www.cve.org/CVERecord?id=CVE-1999-0511](https://www.cve.org/CVERecord?id=CVE-1999-0511)

## Related threats

- [Microsoft Windows NT OS Kernel privilege escalation via integer underflow](https://junglewise.ai/threats/cve-2026-42980-microsoft-windows-nt-os-kernel-privilege-escalation-via-integer)
- [Microsoft Windows NT OS Kernel privilege escalation via integer underflow](https://junglewise.ai/threats/cve-2026-42916-microsoft-windows-nt-os-kernel-privilege-escalation-via-integer)
- [Microsoft DirectX NULL byte overwrite in QuickTime Movie Parser Filter](https://junglewise.ai/threats/cve-2009-1537-microsoft-directx-null-byte-overwrite-in-quicktime-movie-parser)
- [Microsoft Windows NT denial of service in SMB logon request](https://junglewise.ai/threats/cve-1999-0225-microsoft-windows-nt-denial-of-service-in-smb-logon-request)
- [Microsoft Windows TCP/IP stack denial of service in IP fragmentation](https://junglewise.ai/threats/cve-1999-0258-microsoft-windows-tcp-ip-stack-denial-of-service-in-ip)