CVE-2000-0390 in Kerberos
Summary
by MITRE
Buffer overflow in krb425_conv_principal function in Kerberos 5 allows remote attackers to gain root privileges.
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Analysis
by VulDB Data Team • 04/21/2026
The vulnerability identified as CVE-2000-0390 represents a critical buffer overflow flaw within the Kerberos 5 authentication system, specifically within the krb425_conv_principal function. This issue stems from inadequate input validation and bounds checking in the Kerberos protocol implementation, which forms the foundation of many enterprise authentication systems. The vulnerability exists in the transition process between Kerberos version 4 and version 5, where the system fails to properly handle principal names that exceed allocated buffer sizes, creating a pathway for malicious exploitation.
The technical flaw manifests when the krb425_conv_principal function processes principal names without sufficient boundary checks, allowing an attacker to craft specially formatted input that overflows the allocated memory buffer. This buffer overflow occurs in the context of Kerberos authentication services, where the function handles the conversion of principal names between different Kerberos versions. The vulnerability is particularly dangerous because it can be exploited remotely, meaning attackers do not need physical access to the target system. The flaw allows for arbitrary code execution with the privileges of the Kerberos service account, which typically runs with elevated system privileges, potentially enabling attackers to achieve root access on affected systems.
The operational impact of this vulnerability extends far beyond individual system compromise, as Kerberos authentication servers serve as critical infrastructure components in enterprise environments. When exploited successfully, the vulnerability allows attackers to bypass authentication mechanisms entirely and gain unauthorized administrative access to the entire Kerberos domain. This creates a cascading effect where compromised Kerberos servers can be used to authenticate as any user within the domain, potentially leading to complete network infiltration. The vulnerability affects systems running Kerberos 5 implementations that include the problematic krb425_conv_principal function, making it particularly dangerous in large enterprise networks where Kerberos is widely deployed for single sign-on and authentication services.
Security professionals should consider this vulnerability in the context of the MITRE ATT&CK framework, where it maps to techniques involving privilege escalation and credential access. The vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and CWE-787, which covers out-of-bounds write operations. Organizations should implement immediate mitigations including applying vendor patches, disabling vulnerable Kerberos services where possible, and implementing network segmentation to limit the attack surface. The vulnerability also highlights the importance of proper input validation and memory management practices in authentication systems, as specified in security standards such as NIST SP 800-161 and ISO/IEC 27035. Regular security assessments and code reviews focusing on buffer handling and memory management should be conducted to prevent similar issues in other authentication components and to maintain the integrity of enterprise security infrastructures.