CVE-2014-2131 in IOS
Summary
by MITRE
The packet driver in Cisco IOS allows remote attackers to cause a denial of service (device reload) via a series of (1) Virtual Switching Systems (VSS) or (2) Bidirectional Forwarding Detection (BFD) packets, aka Bug IDs CSCug41049 and CSCue61890.
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Analysis
by VulDB Data Team • 05/09/2026
The vulnerability described in CVE-2014-2131 represents a critical denial of service weakness within Cisco IOS packet driver implementations that specifically affects Virtual Switching Systems and Bidirectional Forwarding Detection protocols. This flaw enables remote attackers to deliberately trigger device reloads through carefully crafted packet sequences, effectively disrupting network operations and potentially causing significant service interruptions across affected Cisco network infrastructure. The vulnerability manifests in two distinct attack vectors, each targeting different network protocols that are fundamental to modern network switching and routing operations.
The technical root cause of this vulnerability lies in insufficient input validation and error handling within the IOS packet driver's processing of VSS and BFD packets. When the system receives malformed or specially crafted packets designed to exploit specific protocol handling behaviors, the packet driver fails to properly validate incoming data structures and does not implement adequate defensive mechanisms to prevent resource exhaustion or state corruption. This leads to the system entering an unstable condition that ultimately results in automatic device reload. The vulnerability specifically targets the packet processing logic that handles these protocols, where the absence of proper bounds checking and protocol state validation allows attackers to manipulate the system into executing unintended code paths that culminate in system restarts.
The operational impact of this vulnerability extends beyond simple service disruption to encompass potential business continuity risks and network reliability concerns. Organizations relying on Cisco IOS devices for core network infrastructure may experience unplanned outages, particularly in environments where VSS and BFD protocols are actively deployed for redundancy and fast failover mechanisms. The remote nature of the attack means that adversaries can exploit this weakness from outside the network perimeter without requiring physical access or authentication credentials, making the vulnerability particularly dangerous for mission-critical network operations. Network administrators may face challenges in identifying the source of outages since the device reloads appear to be system failures rather than malicious attacks, complicating incident response and forensic analysis efforts.
Mitigation strategies for this vulnerability require immediate implementation of Cisco's recommended security patches and firmware updates that address the specific packet validation flaws in the IOS packet driver. Network administrators should also consider implementing access control lists and packet filtering rules to restrict incoming VSS and BFD traffic from untrusted sources, though this approach provides only partial protection since the vulnerability exists at the protocol processing level. The implementation of intrusion detection systems with signature-based detection capabilities for known attack patterns related to this vulnerability can help identify exploitation attempts. Additionally, organizations should conduct thorough network topology reviews to identify all devices running affected IOS versions and ensure proper patch management procedures are in place to prevent future similar vulnerabilities. This vulnerability aligns with CWE-129, which describes improper validation of input boundaries, and maps to ATT&CK technique T1499.004 for network disruption attacks that specifically target device availability through denial of service mechanisms.