CVE-2003-0082 in Kerberos
Summary
by MITRE
The Key Distribution Center (KDC) in Kerberos 5 (krb5) 1.2.7 and earlier allows remote, authenticated attackers to cause a denial of service (crash) on KDCs within the same realm using a certain protocol request that causes the KDC to corrupt its heap (aka "buffer underrun").
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Analysis
by VulDB Data Team • 08/25/2025
The vulnerability identified as CVE-2003-0082 represents a critical heap corruption flaw within the Key Distribution Center implementation of Kerberos 5 version 1.2.7 and earlier. This vulnerability exists within the authentication infrastructure that forms the backbone of many enterprise security systems, particularly those utilizing the Kerberos protocol for single sign-on capabilities. The flaw specifically targets the KDC component which serves as the central authority for issuing authentication tickets and managing cryptographic keys within a Kerberos realm. The vulnerability arises from inadequate input validation and memory management practices within the protocol handling code.
The technical exploitation of this vulnerability occurs when an authenticated attacker submits a specially crafted protocol request to the KDC server. This particular request triggers a buffer underrun condition that corrupts the heap memory structure of the KDC process. The heap corruption manifests as the KDC attempting to write data beyond the allocated memory boundaries, causing memory corruption that ultimately leads to process termination and system crash. This type of vulnerability falls under the CWE-121 category of "Stack-based Buffer Overflow" and specifically aligns with ATT&CK technique T1499.100 related to network denial of service attacks. The flaw demonstrates poor memory management practices where the KDC fails to properly validate the length of incoming data before processing it, allowing malicious input to overwrite adjacent memory regions.
The operational impact of this vulnerability extends far beyond simple service disruption, as the KDC serves as the cornerstone of Kerberos-based authentication systems. When a KDC crashes due to this heap corruption, it creates a cascading effect throughout the entire realm, as all authentication services relying on that KDC become unavailable. This disruption can affect hundreds or thousands of users within the organization, as they lose access to network resources, file servers, and applications that depend on Kerberos authentication. The vulnerability is particularly dangerous because it requires only authenticated access to exploit, meaning that an attacker who has obtained legitimate credentials within the realm can leverage this flaw to cause significant operational damage. Organizations using affected Kerberos versions face potential business disruption, increased administrative overhead for system recovery, and potential compromise of their authentication infrastructure.
Mitigation strategies for this vulnerability should prioritize immediate patching of all affected Kerberos implementations to version 1.2.8 or later, which contains the necessary memory validation fixes. System administrators should also implement network segmentation to limit access to KDC servers and restrict authentication requests to trusted sources only. Additional defensive measures include monitoring for unusual authentication patterns that might indicate exploitation attempts, implementing intrusion detection systems capable of identifying malformed Kerberos requests, and maintaining redundant KDC infrastructure to minimize the impact of potential crashes. Organizations should also conduct thorough security assessments of their Kerberos implementations to identify any other potential memory corruption vulnerabilities. The remediation process must include comprehensive testing of patched systems to ensure that the vulnerability has been fully addressed without introducing new compatibility issues. This vulnerability highlights the critical importance of proper memory management in security-critical systems and serves as a reminder that even authenticated attackers can cause significant damage through carefully crafted protocol requests that exploit fundamental memory handling flaws.