CVE-2004-2646 in Free Web Chat
Summary
by MITRE
The addUser function in UserManager.java in Free Web Chat 2.0 allows remote attackers to cause a denial of service (uncaught NullPointerException) via unknown attack vectors that cause the usrName variable to be null.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 04/27/2025
The vulnerability identified as CVE-2004-2646 represents a critical denial of service weakness within the Free Web Chat 2.0 application's user management subsystem. This flaw exists in the addUser function of the UserManager.java file where the system fails to properly validate input parameters before processing them. The specific issue manifests when the usrName variable becomes null during the user addition process, leading to an uncaught NullPointerException that crashes the application and renders it unavailable to legitimate users. This type of vulnerability falls under the category of improper error handling and input validation failures that have been consistently documented in cybersecurity frameworks as particularly dangerous due to their potential for causing system-wide disruptions.
The technical exploitation of this vulnerability occurs through carefully crafted attack vectors that manipulate the application's input processing to force the usrName variable into a null state. When the addUser function attempts to process this null value without proper null checking mechanisms, the application encounters a NullPointerException that is not gracefully handled by the system's error management protocols. This results in an application crash that terminates the service and prevents legitimate users from accessing the chat functionality. The vulnerability demonstrates a classic lack of defensive programming practices where the application does not implement proper null value validation before attempting operations on user-provided data. According to CWE classification systems, this represents a CWE-476: NULL Pointer Dereference vulnerability where the application fails to check for null values before dereferencing pointers, a pattern that has been consistently flagged as a high-risk security issue in software development practices.
The operational impact of this vulnerability extends beyond simple service disruption to potentially affect the availability and reliability of the entire chat platform. When exploited, the denial of service condition can be maintained by repeatedly sending malicious inputs that trigger the null pointer exception, leading to sustained unavailability of the service. This type of attack can be particularly damaging in environments where chat services are critical for business operations or user communication. The vulnerability also exposes the underlying security architecture of the application to potential exploitation by attackers who may use the service disruption as a stepping stone for more sophisticated attacks. From an ATT&CK framework perspective, this vulnerability aligns with techniques related to service disruption and availability attacks, where adversaries seek to compromise system availability as a primary objective rather than direct data access or privilege escalation. Organizations deploying Free Web Chat 2.0 should consider implementing input sanitization, null value validation, and robust error handling mechanisms to prevent such vulnerabilities from being exploited.
Mitigation strategies for this vulnerability should focus on implementing comprehensive input validation and defensive programming practices within the UserManager.java file. The addUser function must be modified to include explicit null checks for the usrName variable before any processing occurs, ensuring that null values are properly handled or rejected. Additionally, the application should implement comprehensive error handling that catches and manages NullPointerException conditions gracefully without allowing them to terminate the application process. Regular security code reviews and static analysis should be conducted to identify similar patterns of improper input validation and error handling across the codebase. Organizations should also consider implementing application-level firewalls or intrusion detection systems that can monitor for unusual patterns of input that might indicate attempts to exploit this vulnerability. The fix should align with secure coding standards and best practices for preventing null pointer dereferences, ensuring that all user-provided inputs are validated and sanitized before processing to maintain system stability and prevent denial of service conditions.