# CVE-1999-0167: Sun Microsystems SunOS NFS file handle prediction vulnerability

Source: https://junglewise.ai/threats/cve-1999-0167-sun-microsystems-sunos-nfs-file-handle-prediction-vulnerability  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 1991-12-06. Updated: 2026-05-10  
License: CC BY 4.0 with a link back

CVE-1999-0167 · Severity: medium · CVSS 4.6 · Published 1991-12-06

A vulnerability in SunOS allows unauthorized users to access files stored on a network file system. By guessing specific file identifiers, an attacker can bypass security controls to read or modify sensitive data. This could lead to the exposure of confidential information or the unauthorized alteration of system files.

Technologies: [Sunos](https://junglewise.ai/threats/technologies/sunos). Vendors: [Sun](https://junglewise.ai/threats/vendors/sun).

## Quick answers

**Is CVE-1999-0167 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-1999-0167 being exploited in the wild.

**How severe is CVE-1999-0167?** Medium severity, with a CVSS score of 4.6, published 6 December 1991.

**Which products and versions are affected?** Sun Microsystems SunOS.

**Is there a fix for CVE-1999-0167?** 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-1999-0167 attacked?** It is attacked with local access, in an operating system.

**Am I affected by CVE-1999-0167?** Check whether you run Sunos. 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 vulnerability stems from the predictable generation of NFS file handles in SunOS. NFS (Network File System) uses these handles to identify files and directories; because they are not sufficiently random or cryptographically secure, an attacker can guess valid handles. This allows a local attacker to bypass standard access controls and interact with the exported file system. Successful exploitation grants unauthorized read, write, or delete permissions on the affected files. This issue is a classic example of weak identifier generation in early network protocols.

## Affected products

- Sun Microsystems SunOS

## Timeline

- 1991-12-06: disclosed: Initial publication date in NVD

## References

- [https://exchange.xforce.ibmcloud.com/vulnerabilities/CVE-1999-0167](https://exchange.xforce.ibmcloud.com/vulnerabilities/CVE-1999-0167)

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