CVE-2006-5395 in Class Package Export Tool
Summary
by MITRE
Buffer overflow in Microsoft Class Package Export Tool (aka clspack.exe) allows context-dependent attackers to execute arbitrary code via a long string. NOTE: the provenance of this information is unknown; the details are obtained from third party information.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 04/25/2026
The vulnerability identified as CVE-2006-5395 represents a critical buffer overflow flaw within Microsoft's Class Package Export Tool, commonly known as clspack.exe. This tool is part of the Microsoft Windows operating system and serves the purpose of packaging and exporting class definitions for COM components. The buffer overflow vulnerability manifests when the application processes input data without adequate bounds checking, specifically when handling excessively long string inputs. The flaw exists in the way clspack.exe manages memory allocation for string buffers, creating a condition where attacker-controlled input can overwrite adjacent memory locations beyond the intended buffer boundaries. This particular vulnerability is classified as context-dependent, meaning that successful exploitation requires specific conditions to be met, typically involving the execution of the vulnerable tool with maliciously crafted input parameters.
The technical implementation of this buffer overflow vulnerability stems from improper input validation mechanisms within the clspack.exe application. When the tool receives a string input that exceeds the predefined buffer size, the excess data overflows into adjacent memory regions, potentially corrupting critical program data or executable code. This memory corruption can lead to arbitrary code execution with the privileges of the user running the application, which typically corresponds to the local system user. The vulnerability falls under CWE-121, which describes Stack-based Buffer Overflow, and may also align with CWE-122 for Heap-based Buffer Overflow depending on the specific memory allocation patterns. The attack vector requires an attacker to either convince a user to execute the vulnerable tool with malicious input or to gain access to a system where the tool is accessible and executable.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with a potential pathway for privilege escalation and system compromise. Since clspack.exe is a legitimate Windows utility, exploitation could occur through various attack vectors including social engineering, compromised software installations, or direct system access. The vulnerability's context-dependent nature suggests that successful exploitation requires specific environmental conditions, potentially limiting its widespread impact but not eliminating the risk entirely. Attackers could leverage this vulnerability to install malware, modify system files, or establish persistent access to compromised systems. The vulnerability also aligns with ATT&CK technique T1059.001 for Command and Scripting Interpreter, where adversaries might use the tool to execute malicious commands through the buffer overflow. Additionally, the vulnerability could be exploited as part of a broader attack chain leading to T1546.003 for Windows Management Instrumentation Event Subscription, where compromised systems might be used to establish persistent backdoors.
Mitigation strategies for CVE-2006-5395 should focus on both immediate protective measures and long-term system hardening. Microsoft has released security updates addressing this vulnerability, and system administrators should prioritize applying these patches to prevent exploitation. Additional protective measures include implementing application whitelisting policies to restrict execution of potentially vulnerable tools, disabling unnecessary system components that might utilize the clspack.exe utility, and monitoring for suspicious execution patterns of the tool. Network segmentation and access controls can limit the potential impact of successful exploitation by restricting lateral movement within compromised environments. The vulnerability also highlights the importance of input validation and secure coding practices, particularly in legacy applications that may not have been designed with modern security considerations in mind. Organizations should conduct comprehensive vulnerability assessments to identify other potentially vulnerable components within their systems and implement regular security testing procedures to detect similar issues before they can be exploited by malicious actors.