# CVE-1999-0123: Linux mailx race condition in file handling

Source: https://junglewise.ai/threats/cve-1999-0123-linux-mailx-race-condition-in-file-handling  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 1995-12-01. Updated: 2026-05-10  
License: CC BY 4.0 with a link back

CVE-1999-0123 · Severity: low · CVSS 3.7 · Published 1995-12-01

A vulnerability exists in the mailx utility, a standard command-line tool used for sending and receiving email on Linux systems. A local attacker could exploit a timing flaw to gain unauthorized access to files belonging to other users on the same system. This could lead to the exposure of sensitive personal or system information.

Technologies: [Slackware Linux](https://junglewise.ai/threats/technologies/slackware-linux). Vendors: [Linux](https://junglewise.ai/threats/vendors/linux), [Slackware](https://junglewise.ai/threats/vendors/slackware).

## Quick answers

**Is CVE-1999-0123 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-1999-0123 being exploited in the wild.

**How severe is CVE-1999-0123?** Low severity, with a CVSS score of 3.7, published 1 December 1995.

**Which products and versions are affected?** Linux mailx.

**Is there a fix for CVE-1999-0123?** 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-1999-0123 attacked?** It is attacked with local access, in an operating system.

**Am I affected by CVE-1999-0123?** Check whether you run Linux Mailx or Slackware Linux. 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

A race condition exists in the Linux mailx command. By exploiting a window of time during file operations, a local authenticated user can perform a symlink attack or similar race-based maneuver to intercept or read files they do not have permission to access. The attack requires local access and specific timing (High Access Complexity), resulting in a partial impact on confidentiality, integrity, and availability. This is a legacy vulnerability originally identified in 1995.

## Affected products

- Linux mailx

## Timeline

- 1995-12-01: disclosed: Initial publication date in NVD

## References

- [https://exchange.xforce.ibmcloud.com/vulnerabilities/CVE-1999-0123](https://exchange.xforce.ibmcloud.com/vulnerabilities/CVE-1999-0123)

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