CVE-2000-0392 in Kerberos
Summary
by MITRE
Buffer overflow in ksu in Kerberos 5 allows local users to gain root privileges.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 04/21/2026
The vulnerability identified as CVE-2000-0392 represents a critical buffer overflow flaw within the ksu component of Kerberos 5, a widely deployed network authentication protocol. This issue specifically affects the ksu utility which serves as a privileged program for switching user identities within the Kerberos framework. The buffer overflow occurs when the ksu program processes user input without proper bounds checking, creating an exploitable condition that can be leveraged by local attackers to execute arbitrary code with elevated privileges.
The technical implementation of this vulnerability stems from improper memory management within the ksu utility's input handling routines. When legitimate users provide input to the ksu program, particularly through command-line arguments or environment variables, the program fails to validate the length of incoming data against allocated buffer space. This allows an attacker to overflow the designated memory buffer and overwrite adjacent memory locations, including return addresses on the stack. The flaw exists in the Kerberos 5 implementation and affects systems where ksu is installed and configured for use.
From an operational perspective, this vulnerability presents a severe privilege escalation risk for local attackers who already have access to the system. The ability to gain root privileges through a buffer overflow in a core authentication utility means that attackers can bypass the entire Kerberos authentication mechanism and assume complete system control. The impact extends beyond immediate privilege escalation as the compromised system can then be used as a launch point for further attacks, data exfiltration, or as a persistent backdoor. This vulnerability undermines the fundamental security assumptions of the Kerberos authentication system and exposes all systems running vulnerable versions of Kerberos 5 to potential compromise.
The mitigation strategy for this vulnerability requires immediate patching of the Kerberos 5 implementation to address the buffer overflow in the ksu utility. System administrators should ensure that all instances of ksu are updated to versions that properly implement input validation and bounds checking. Additionally, security hardening measures should be implemented including disabling unnecessary ksu usage, implementing proper access controls, and monitoring for suspicious ksu executions. The vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and represents a classic example of how privilege escalation vulnerabilities can be exploited through memory corruption flaws. Organizations should also consider implementing runtime protections such as stack canaries, address space layout randomization, and other exploit mitigations to reduce the effectiveness of potential exploitation attempts. This vulnerability demonstrates the critical importance of proper input validation in privileged programs and highlights the need for comprehensive security testing of authentication components within enterprise security infrastructures.