CVE-1999-1406 is a vulnerability identified in the dumpreg utility of Red Hat Linux version 5.1. The issue arises because dumpreg opens the /dev/mem device file with read-write (O_RDWR) access. /dev/mem is a special file that provides access to the physical memory of the system, including kernel memory. By opening this device with read-write permissions, dumpreg inadvertently allows local users to manipulate kernel memory indirectly. Specifically, an attacker can redirect the standard output file descriptor (fd 1) to /dev/mem, which can cause the kernel to crash, resulting in a denial of service (DoS). This vulnerability requires local user access, meaning an attacker must already have some level of access to the system to exploit it. The impact is limited to causing a system crash, with no direct confidentiality or integrity compromise reported. The vulnerability was published in 1998 and affects an outdated version of Red Hat Linux (5.1). There is no patch available for this vulnerability, and no known exploits have been reported in the wild. The CVSS v2 score is 2.1, indicating a low severity primarily due to the requirement for local access and the limited impact scope (denial of service only).

For European organizations, the direct impact of this vulnerability is minimal in modern contexts because Red Hat Linux 5.1 is an obsolete operating system version that is no longer in use in production environments. However, if legacy systems running this version are still operational, the vulnerability could be exploited by local users to cause system crashes, leading to downtime and potential disruption of services. This could affect availability of critical systems, especially in environments where uptime is crucial. Since the vulnerability does not allow privilege escalation or data compromise, the risk to confidentiality and integrity is low. Nonetheless, any denial of service in critical infrastructure or industrial control systems could have cascading effects. European organizations with legacy Linux systems in isolated or controlled environments should be aware of this risk, although it is unlikely to be a widespread threat today.

Given the age of the affected system, the most effective mitigation is to upgrade or migrate from Red Hat Linux 5.1 to a supported and actively maintained Linux distribution version. If upgrading is not immediately feasible, organizations should restrict local user access to trusted personnel only and implement strict access controls to prevent unauthorized local logins. Additionally, monitoring for unusual file descriptor manipulations or attempts to access /dev/mem could help detect exploitation attempts. Employing mandatory access control frameworks such as SELinux or AppArmor (if backported or available) could limit the ability of dumpreg or other utilities to open /dev/mem with write permissions. Finally, isolating legacy systems from critical network segments can reduce the risk of exploitation impacting broader infrastructure.