CVE-2014-2155 in CNS Network Registrar Central Configuration Management
Summary
by MITRE
The DHCPv6 server module in Cisco CNS Network Registrar 7.1 allows remote attackers to cause a denial of service (daemon reload) via a malformed DHCPv6 packet, aka Bug ID CSCuo07437.
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Analysis
by VulDB Data Team • 05/11/2026
The vulnerability identified as CVE-2014-2155 affects the DHCPv6 server module within Cisco CNS Network Registrar version 7.1, representing a critical denial of service weakness that can be exploited by remote attackers. This issue stems from inadequate input validation mechanisms within the DHCPv6 server implementation, specifically when processing incoming DHCPv6 packets. The flaw manifests when the system receives a malformed DHCPv6 packet that triggers an unexpected daemon reload operation, effectively disrupting the network infrastructure services that depend on this registrar for dynamic host configuration protocol version 6 functionality.
The technical exploitation of this vulnerability occurs through the crafting of specially malformed DHCPv6 packets that, when processed by the vulnerable Network Registrar server, cause the system to reload its daemon processes. This reload operation results in temporary unavailability of DHCPv6 services, preventing legitimate clients from obtaining network configuration parameters such as IP addresses, DNS servers, and other essential network settings. The vulnerability's impact is particularly severe in enterprise environments where continuous network availability is critical for business operations, as the daemon reload effectively creates a service interruption that can last several seconds to minutes depending on the system configuration and resource availability.
From a cybersecurity perspective, this vulnerability aligns with CWE-129, which describes improper validation of input boundaries, and represents a classic example of a buffer overflow or input sanitization failure that leads to service disruption. The attack vector is remote and requires no authentication, making it particularly dangerous as it can be exploited by any attacker with network access to the affected system. The ATT&CK framework categorizes this as a Denial of Service technique under the T1499 category, specifically targeting network infrastructure components to create service interruptions that can have cascading effects on dependent systems and applications within the network environment.
Organizations utilizing Cisco CNS Network Registrar 7.1 should implement immediate mitigations including network segmentation to limit access to DHCPv6 services, deployment of network access control measures to restrict unauthorized packet transmission, and implementation of intrusion detection systems that can identify and alert on malformed DHCPv6 traffic patterns. The most effective long-term solution involves upgrading to patched versions of Cisco CNS Network Registrar that address the input validation weaknesses in the DHCPv6 server module. Additionally, implementing rate limiting mechanisms on DHCPv6 traffic and regular monitoring of daemon reload events can help detect exploitation attempts and provide early warning of potential attacks. System administrators should also consider implementing redundant DHCPv6 services to minimize the impact of such disruptions on network availability and ensure business continuity during potential exploitation events.