CVE-2006-3083 in Kerberos
Summary
by MITRE
The (1) krshd and (2) v4rcp applications in (a) MIT Kerberos 5 (krb5) up to 1.5, and 1.4.x before 1.4.4, when running on Linux and AIX, and (b) Heimdal 0.7.2 and earlier, do not check return codes for setuid calls, which allows local users to gain privileges by causing setuid to fail to drop privileges using attacks such as resource exhaustion.
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Analysis
by VulDB Data Team • 06/21/2025
The vulnerability described in CVE-2006-3083 represents a critical privilege escalation flaw affecting authentication systems that utilize Kerberos implementations. This issue specifically impacts the krshd and v4rcp applications within both MIT Kerberos 5 versions up to 1.5 and 1.4.x before 1.4.4, as well as Heimdal 0.7.2 and earlier versions. These applications are designed to operate with elevated privileges through setuid mechanisms to perform necessary authentication functions, but the flaw lies in their failure to properly validate the return codes from these privileged operations.
The technical root cause of this vulnerability stems from improper error handling within the setuid execution flow. When these applications execute setuid operations to drop privileges after performing authentication tasks, they fail to check whether the setuid system call actually succeeded. This omission creates a scenario where if the setuid operation fails due to resource exhaustion or other system limitations, the application continues execution with elevated privileges instead of properly dropping them. The vulnerability is particularly dangerous because it allows local users to exploit this weakness by forcing the system into a state where setuid calls fail, thereby maintaining root or administrative privileges that should have been relinquished.
This flaw directly maps to CWE-252, which describes "Unchecked Return Value," and represents a classic example of insufficient error handling in privilege management contexts. The operational impact of this vulnerability is severe as it enables local attackers to escalate their privileges from regular user accounts to root or administrative levels without requiring any special authentication credentials. Attackers can leverage resource exhaustion techniques or other system stress conditions to force the setuid calls to fail, thereby maintaining elevated privileges throughout the application's execution. This vulnerability effectively undermines the fundamental security principle of least privilege that Kerberos implementations are designed to enforce.
The attack surface for this vulnerability extends across multiple platforms including Linux and AIX systems running affected Kerberos implementations, making it particularly dangerous in enterprise environments where these systems are commonly deployed. The exploitability of this vulnerability is enhanced by the fact that it requires no network access or authentication credentials, making it a local privilege escalation vector that can be exploited by any user with access to the affected system. Organizations implementing these vulnerable Kerberos versions face significant risk as this flaw allows attackers to potentially gain complete system control without detection, as the privilege escalation occurs silently within the normal application execution flow.
Mitigation strategies for this vulnerability require immediate patching of affected Kerberos implementations to versions that properly validate setuid return codes. System administrators should ensure that all instances of MIT Kerberos 5 are updated to version 1.4.4 or later, and that Heimdal installations are upgraded to versions greater than 0.7.2. Additionally, security monitoring should be enhanced to detect unusual privilege escalation patterns and setuid execution failures. The implementation of proper error handling and return code validation should be enforced across all setuid applications within the organization's security infrastructure. Organizations should also consider implementing privilege separation techniques and regular security audits to identify similar vulnerabilities in other system components that may exhibit similar error handling flaws. This vulnerability serves as a reminder of the critical importance of proper error handling in security-sensitive code and the potential consequences of overlooking fundamental privilege management mechanisms.