# CVE-1999-1138: SCO UNIX insecure home directory permissions for system accounts

Source: https://junglewise.ai/threats/cve-1999-1138-sco-unix-insecure-home-directory-permissions-for-system-accounts  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 1993-09-17. Updated: 2026-05-10  
License: CC BY 4.0 with a link back

CVE-1999-1138 · Severity: critical · CVSS 10 · Published 1993-09-17

A security flaw in SCO UNIX operating systems allows unauthorized users to take control of specific system accounts. This occurs because certain system accounts were configured to use public temporary folders as their home directories. An attacker with access to the system could use this to gain elevated privileges, potentially leading to a full system compromise.

Vendors: [Sco](https://junglewise.ai/threats/vendors/sco).

## Quick answers

**Is CVE-1999-1138 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-1999-1138 being exploited in the wild.

**How severe is CVE-1999-1138?** Critical severity, with a CVSS score of 10, published 17 September 1993.

**Which products and versions are affected?** Sco Open Desktop All versions; Sco UNIX System V/386 3.2.

**Is there a fix for CVE-1999-1138?** 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-1999-1138 attacked?** It is attacked with local access, in an operating system.

**Am I affected by CVE-1999-1138?** Check whether you run Sco Open Desktop or Sco UNIX System V/386 at an affected version. 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 arises from an insecure default configuration where the 'dos' and 'asg' system accounts are assigned world-writable home directories (/tmp and /usr/tmp, respectively). Because any user on the system can write to these directories, an attacker can place malicious initialization files (such as .profile or .login) or manipulate environment settings to execute arbitrary code when these accounts are accessed. This is a local privilege escalation vector that can lead to full administrative control if these accounts have high-level permissions or if further lateral movement is possible. The issue was originally identified in SCO UNIX System V/386 Release 3.2 and SCO Open Desktop.

## Affected products

- SCO UNIX System V/386 3.2
- SCO Open Desktop All versions

## Timeline

- 1993-09-17: disclosed
- 1993-09-17: advisory: NVD publication date

## References

- [http://www.cert.org/advisories/CA-1993-13.html](http://www.cert.org/advisories/CA-1993-13.html)
- [https://exchange.xforce.ibmcloud.com/vulnerabilities/546](https://exchange.xforce.ibmcloud.com/vulnerabilities/546)

## Related threats

- [SCO OpenServer scoterm privilege escalation](https://junglewise.ai/threats/cve-1999-1209-sco-openserver-scoterm-privilege-escalation)