CVE-2004-2646
Description
Free Web Chat 2.0's addUser function is vulnerable to a NullPointerException, allowing remote attackers to cause a denial of service.
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
Free Web Chat 2.0's addUser function is vulnerable to a NullPointerException, allowing remote attackers to cause a denial of service.
Vulnerability
The addUser function in UserManager.java within Free Web Chat version 2.0 is susceptible to a denial of service vulnerability. This occurs when the usrName variable is null, leading to an uncaught NullPointerException.
Exploitation
A remote attacker can exploit this vulnerability by sending crafted requests that result in the usrName variable being null. The exact attack vectors are not fully detailed, but the provided proof-of-concept code demonstrates how to connect to the server and potentially trigger the vulnerability [1].
Impact
Successful exploitation of this vulnerability allows a remote attacker to cause a denial of service, preventing legitimate users from accessing the chat service. The impact is limited to service disruption.
Mitigation
There is no specific patched version or mitigation strategy disclosed in the available references for this vulnerability. Users are advised to check for updates from the vendor or consider alternative solutions if a patch is not available.
AI Insight generated on Jun 1, 2026. Synthesized from this CVE's description and the cited reference URLs; citations are validated against the source bundle.
Affected products
1- Range: =2.0
Patches
0No patches discovered yet.
Vulnerability mechanics
Root cause
"The addUser function does not properly handle a null username, leading to a NullPointerException."
Attack vector
A remote attacker can exploit this vulnerability by sending a request that causes the usrName variable to be null when calling the addUser function. This lack of sufficient sanitization on username data allows a user with a void name to be added, triggering a NullPointerException. The advisory does not specify the exact attack vectors or payload shape that lead to this condition [ref_id=1].
Affected code
The vulnerability resides in the addUser function within the UserManager.java file of Free Web Chat version 2.0. The issue stems from insufficient sanitization of username data, specifically when the usrName variable is null [ref_id=1].
What the fix does
The patch is not available in the provided information. The advisory suggests that the vulnerability is caused by a lack of sufficient sanitization performed on username data, which allows a user with a void name to be added, resulting in a NullPointerException [ref_id=1]. Remediation would involve properly validating and sanitizing the username input before it is processed by the addUser function.
Preconditions
- networkThe attacker must be able to send network requests to the Free Web Chat server.
- inputThe attacker must be able to craft a request that results in a null value for the username parameter.
Reproduction
The provided reference write-up includes a Proof of Concept (PoC) C code that demonstrates how to connect to the Free Web Chat server and potentially trigger the denial of service vulnerability. However, the specific steps to trigger the NullPointerException by sending a null username are not detailed in the PoC code itself, only implied by the vulnerability description [ref_id=1].
Generated on Jun 2, 2026. Inputs: CWE entries + fix-commit diffs from this CVE's patches. Citations validated against bundle.
References
6News mentions
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