CVE-2006-4397 in Mac OS X
Summary
by MITRE
Unchecked error condition in LoginWindow in Apple Mac OS X 10.4 through 10.4.7 prevents Kerberos tickets from being destroyed if a user does not successfully log on to a network account from the login window, which might allow later users to gain access to the original user's Kerberos tickets.
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Analysis
by VulDB Data Team • 04/23/2026
The vulnerability described in CVE-2006-4397 represents a critical security flaw in Apple Mac OS X versions 10.4 through 10.4.7, specifically within the LoginWindow component responsible for user authentication processes. This issue stems from an unchecked error condition that fails to properly handle authentication failures when users attempt to log into network accounts through the graphical login interface. The flaw operates at the system level where the login process does not adequately validate or manage error states, creating a persistent security risk that extends beyond the immediate authentication attempt.
The technical implementation of this vulnerability involves the Kerberos authentication mechanism, which is a network authentication protocol designed to provide strong authentication for client-server applications by using secret-key cryptography. When a user attempts to log into a network account through the LoginWindow and the authentication process fails, the system should properly destroy or invalidate the Kerberos tickets that were generated during the failed authentication attempt. However, due to the unchecked error condition, these tickets remain active in memory or on disk, creating a window of opportunity for unauthorized access.
This vulnerability directly impacts the principle of least privilege and authentication integrity by allowing unauthorized users to potentially access network resources that should only be available to the original authenticated user. The operational impact is significant as it creates a persistent backdoor where subsequent users can exploit the cached Kerberos tickets to gain access to network services and resources that were originally intended for the failed login attempt. The flaw essentially creates a credential replay attack vector where authentication artifacts are not properly cleaned up after failed login attempts.
From a cybersecurity perspective, this vulnerability aligns with CWE-254, which addresses security weaknesses related to improper error handling and the failure to properly manage authentication state. The issue also maps to ATT&CK technique T1550.003, which involves using Kerberos tickets for privilege escalation and lateral movement. The vulnerability demonstrates poor input validation and error handling practices within the system's authentication framework, where the failure to properly manage authentication artifacts creates a persistent security exposure that can be exploited by attackers with access to the system.
The mitigation strategies for this vulnerability involve both immediate system updates and operational security measures. Apple addressed this issue through system updates that properly implemented error handling for the LoginWindow component, ensuring that Kerberos tickets are destroyed or invalidated upon failed authentication attempts. Organizations should implement regular patch management protocols to ensure all systems receive timely security updates. Additionally, network administrators should monitor for unauthorized access attempts and implement network segmentation to limit the potential impact of credential compromise. The vulnerability highlights the importance of proper authentication state management and the need for comprehensive error handling in security-critical system components, particularly those handling sensitive authentication artifacts like Kerberos tickets.