CVE-2014-2124 in IOS
Summary
by MITRE
Cisco IOS 15.1(2)SY3 and earlier, when used with Supervisor Engine 2T (aka Sup2T) on Catalyst 6500 devices, allows remote attackers to cause a denial of service (device crash) via crafted multicast packets, aka Bug ID CSCuf60783.
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Analysis
by VulDB Data Team • 05/08/2026
The vulnerability identified as CVE-2014-2124 represents a critical denial of service flaw affecting Cisco IOS software versions 15.1(2)SY3 and earlier when deployed on Catalyst 6500 series switches equipped with Supervisor Engine 2T. This weakness specifically targets the multicast packet processing functionality within the IOS operating system, creating a scenario where maliciously crafted multicast traffic can trigger a complete device crash. The vulnerability was documented under Bug ID CSCuf60783 and demonstrates a fundamental flaw in how the system handles certain multicast packet structures, particularly those involving specific header configurations that cause the supervisor engine to enter an unstable state.
The technical implementation of this vulnerability exploits a buffer handling issue within the multicast routing protocols processing module of IOS. When the Sup2T supervisor engine receives specially crafted multicast packets containing malformed or unexpected header values, the packet processing routine fails to properly validate the incoming data structures. This leads to memory corruption within the routing table management system, ultimately causing the supervisor engine to crash and restart automatically. The flaw resides in the lack of proper input validation and bounds checking during multicast packet parsing, which aligns with common CWE categories related to buffer overflows and improper input validation. The vulnerability is particularly concerning because it operates at the network infrastructure level, where switches serve as critical communication hubs in enterprise and service provider networks.
The operational impact of this vulnerability extends beyond simple device downtime, as it can severely disrupt network operations and create cascading failures throughout the affected infrastructure. When a Catalyst 6500 switch with Sup2T crashes due to this vulnerability, it can cause complete network segmentation, as multicast traffic typically flows through multiple network segments and relies heavily on proper switch functionality. Network administrators may experience extended periods of service disruption while the device recovers and re-establishes routing tables. The remote nature of this attack means that adversaries can exploit the vulnerability from outside the network perimeter, making it particularly dangerous for service providers and enterprise networks that may not have proper network segmentation in place. This vulnerability directly impacts the availability aspect of the CIA triad and can be classified under ATT&CK technique T1499.002 for network denial of service attacks.
Mitigation strategies for CVE-2014-2124 require immediate attention from network administrators and security teams responsible for maintaining Cisco infrastructure. The primary recommended solution involves applying the appropriate Cisco IOS software patches and updates that address the multicast packet processing flaw in the Sup2T supervisor engine. Organizations should also implement network segmentation strategies to limit the impact of potential exploitation attempts, including deploying multicast filtering rules and access control lists to restrict multicast traffic at network boundaries. Network monitoring systems should be configured to detect unusual multicast traffic patterns that might indicate exploitation attempts. Additionally, implementing redundant network paths and failover mechanisms can help maintain service availability during potential exploitation events. The vulnerability highlights the importance of regular security patch management and continuous monitoring of network infrastructure for known vulnerabilities, particularly those affecting core network devices that serve as critical infrastructure components.