CVE-2018-0167 in IOS
Summary
by MITRE
Multiple Buffer Overflow vulnerabilities in the Link Layer Discovery Protocol (LLDP) subsystem of Cisco IOS Software, Cisco IOS XE Software, and Cisco IOS XR Software could allow an unauthenticated, adjacent attacker to cause a denial of service (DoS) condition or execute arbitrary code with elevated privileges on an affected device. Cisco Bug IDs: CSCuo17183, CSCvd73487.
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Analysis
by VulDB Data Team • 10/28/2025
The vulnerability CVE-2018-0167 represents a critical buffer overflow issue within the Link Layer Discovery Protocol (LLDP) implementation across multiple Cisco software platforms including IOS, IOS XE, and IOS XR. This flaw exists in the handling of LLDP packets received from adjacent network devices, creating a significant security risk for network infrastructure. The vulnerability specifically affects the LLDP subsystem which is responsible for enabling network devices to advertise their identity, capabilities, and configuration information to neighboring devices. When an attacker crafts malicious LLDP packets with oversized or malformed data fields, the vulnerable software fails to properly validate input lengths, leading to memory corruption that can result in system instability.
The technical exploitation of this vulnerability occurs through the improper handling of buffer boundaries in the LLDP packet processing code. When the system receives LLDP frames containing oversized TLV (Type-Length-Value) structures or malformed data sequences, the memory allocation routines do not adequately check buffer limits before copying data into fixed-size memory regions. This classic buffer overflow condition allows an attacker to overwrite adjacent memory locations, potentially corrupting critical system data structures or even executing arbitrary code. The vulnerability is particularly dangerous because it requires no authentication and only needs network adjacency, making it exploitable from within the local network segment. According to the CWE classification, this represents a CWE-121: Stack-based Buffer Overflow, while the ATT&CK framework would categorize this under T1499.004: Endpoint Denial of Service and potentially T1059.001: Command and Scripting Interpreter for code execution scenarios.
The operational impact of CVE-2018-0167 extends beyond simple denial of service conditions to potentially enable complete system compromise. A successful exploit can cause immediate device crashes and reboots, disrupting network connectivity and service availability for extended periods. In more severe cases, the buffer overflow may allow privilege escalation, enabling attackers to execute code with elevated system privileges and potentially gain full control over the affected network device. This could result in complete network infrastructure compromise, as routers, switches, and other network equipment running vulnerable software become potential entry points for broader network attacks. The vulnerability affects critical network infrastructure components that form the backbone of enterprise and service provider networks, making the impact particularly severe for organizations relying on Cisco networking equipment. Organizations may experience significant downtime, service interruptions, and potential data exposure when these devices are compromised, with recovery efforts potentially requiring complete device reinstallation and reconfiguration.
Mitigation strategies for CVE-2018-0167 should focus on both immediate defensive measures and long-term remediation approaches. Cisco has released patches and software updates addressing this vulnerability, which should be applied immediately to all affected systems. Network administrators should implement LLDP filtering and disable LLDP functionality on interfaces where it is not required, reducing the attack surface. Network segmentation and access control measures can help limit the ability of adjacent attackers to reach vulnerable devices. Additionally, monitoring systems should be configured to detect unusual LLDP traffic patterns that might indicate exploitation attempts. The implementation of network access control lists and firewall rules to restrict LLDP traffic can provide additional layers of protection. Organizations should also conduct comprehensive vulnerability assessments to identify all devices running affected software versions and prioritize patching efforts based on risk exposure. Regular network monitoring and intrusion detection system updates are essential to detect potential exploitation attempts and maintain overall network security posture against similar vulnerabilities.