CVE-2006-4511 in GroupWise
Summary
by MITRE
Messenger Agents (nmma.exe) in Novell GroupWise 2.0.2 and 1.0.6 allows remote attackers to cause a denial of service (crash) via a crafted HTTP POST request to TCP port 8300 with a modified val parameter, which triggers a null dereference related to "zero-size strings in blowfish routines."
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 04/23/2026
The vulnerability identified as CVE-2006-4511 affects Novell GroupWise Messenger Agents (nmma.exe) version 2.0.2 and 1.0.6, representing a critical denial of service weakness that can be exploited remotely through crafted HTTP POST requests. This flaw specifically targets TCP port 8300 which serves as the communication endpoint for the messenger agent service, making it a prime target for network-based attacks that can disrupt business operations and communication services within organizations relying on GroupWise messaging infrastructure.
The technical root cause of this vulnerability stems from improper input validation within the blowfish encryption routines used by the messenger agent software. When a malicious actor sends a crafted HTTP POST request containing a modified val parameter to the designated port, the system processes this input without adequate sanitization, leading to a null pointer dereference condition. This particular flaw manifests when the software encounters zero-size strings during blowfish encryption operations, causing the application to crash and terminate unexpectedly. The vulnerability operates at the application layer and requires no authentication, making it particularly dangerous as it can be exploited by any remote attacker with network access to the target system.
The operational impact of this vulnerability extends beyond simple service disruption, as it can severely compromise the availability of critical communication infrastructure within enterprise environments. Organizations using Novell GroupWise messaging systems face the risk of unauthorized personnel causing system-wide outages through simple network-based attacks that require minimal technical expertise. The crash condition affects the messenger agent process itself, potentially leading to cascading failures if the service is critical to other applications or if the system lacks proper process monitoring and restart mechanisms. This vulnerability directly aligns with CWE-476 which addresses null pointer dereference conditions, and represents a classic example of how cryptographic routine flaws can be exploited for denial of service attacks.
Mitigation strategies for this vulnerability should focus on immediate patch deployment from Novell, as the manufacturer would have released a software update addressing the input validation issues within the blowfish routines. Network administrators should implement firewall rules to restrict access to TCP port 8300, particularly from untrusted networks, while also considering network segmentation to limit the attack surface. Additionally, implementing intrusion detection systems that can identify and alert on suspicious HTTP POST requests containing malformed val parameters would provide early warning capabilities. From an ATT&CK framework perspective, this vulnerability maps to the T1499.004 technique for network denial of service, and organizations should consider implementing process monitoring to detect and automatically restart crashed messenger agent processes to minimize downtime impact. The vulnerability also highlights the importance of input validation in cryptographic libraries and demonstrates how seemingly minor implementation flaws can lead to significant operational disruptions in enterprise messaging systems.