CVE-1999-1406 in Linux
Summary
by MITRE
dumpreg in Red Hat Linux 5.1 opens /dev/mem with O_RDWR access, which allows local users to cause a denial of service (crash) by redirecting fd 1 (stdout) to the kernel.
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Analysis
by VulDB Data Team • 04/17/2026
The vulnerability identified as CVE-1999-1406 resides in the dumpreg utility distributed with Red Hat Linux 5.1, representing a classic case of improper privilege handling and file descriptor management. This flaw demonstrates how seemingly benign system utilities can present significant security risks when not properly secured against local exploitation attempts. The dumpreg utility is designed to dump register information from the kernel, but its implementation contains a critical design flaw that directly impacts system stability and security posture.
The technical implementation of this vulnerability stems from the dumpreg utility's approach to accessing kernel memory through the /dev/mem device file. When the utility opens /dev/mem with O_RDWR permissions, it grants unnecessary read-write access to kernel memory regions that should typically be restricted to privileged kernel components. This design choice creates an exploitable condition where local users can manipulate file descriptor 1, which represents stdout, to redirect it to kernel memory locations. The redirection causes the utility to write kernel data to stdout, which in turn triggers a system crash or denial of service condition due to the utility's inability to handle kernel memory access violations gracefully.
This vulnerability directly maps to CWE-242, which describes the weakness of using potentially dangerous functions that can lead to system instability and resource exhaustion. The flaw also aligns with ATT&CK technique T1499.001, which covers network denial of service attacks, though in this case the attack vector is local rather than network-based. The vulnerability represents a privilege escalation vector that allows local users to cause system instability, effectively creating a denial of service condition that can impact system availability and potentially compromise the integrity of the system's runtime environment.
The operational impact of this vulnerability extends beyond simple system crashes, as it demonstrates a fundamental flaw in how system utilities handle kernel memory access and file descriptor redirection. Local users with minimal privileges can leverage this condition to disrupt system operations, potentially causing service interruptions that affect system availability and user productivity. The vulnerability also highlights the importance of proper privilege separation and the principle of least privilege in system design, as the utility unnecessarily requests elevated permissions that are not required for its intended function.
Mitigation strategies for this vulnerability should focus on modifying the dumpreg utility to properly handle kernel memory access without requiring unnecessary O_RDWR permissions. The recommended approach involves implementing proper file descriptor management that prevents redirection of stdout to kernel memory regions, as well as ensuring that kernel memory access is properly restricted through appropriate access controls and permission checks. System administrators should also implement monitoring for unusual file descriptor behavior and consider restricting access to the dumpreg utility to authorized users only. Additionally, the vulnerability underscores the importance of regular security audits of system utilities and the need for proper input validation and privilege management in all system components, particularly those that interface with kernel memory regions. The fix should ensure that utilities requesting kernel memory access do so through proper kernel interfaces rather than direct device file access, thereby reducing the attack surface and preventing similar vulnerabilities from emerging in other system components.