CVE-2018-0175 in IOS
Summary
by MITRE
Format String vulnerability 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: CSCvd73664.
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Analysis
by VulDB Data Team • 10/28/2025
The vulnerability identified as CVE-2018-0175 represents a critical format string flaw within the Link Layer Discovery Protocol (LLDP) implementation across multiple Cisco networking platforms including IOS, IOS XE, and IOS XR software versions. This weakness exists in the LLDP subsystem which is responsible for enabling network devices to advertise their identity, capabilities, and location to neighboring devices on a local network segment. The format string vulnerability arises when the system processes malformed LLDP packets containing specially crafted format specifiers that are improperly handled during string formatting operations. Such flaws typically occur when user-supplied input is directly used in printf-style functions without proper validation or sanitization, creating opportunities for attackers to manipulate memory layout and execution flow.
The security implications of this vulnerability extend beyond simple denial of service conditions to potentially enabling arbitrary code execution with elevated privileges on affected network devices. An unauthenticated attacker positioned within the same broadcast domain as the target device can exploit this weakness by transmitting malicious LLDP frames containing crafted format specifiers that trigger the vulnerable code path. When the system attempts to process these malformed packets, the improper string formatting can lead to stack corruption, memory overwrite conditions, or controlled execution flow manipulation. This vulnerability directly maps to CWE-134 which specifically addresses the use of user-supplied format strings in functions like printf, sprintf, and related formatting routines. The attack vector requires physical proximity to the target device since LLDP operates at the data link layer and typically only accepts packets from directly connected network segments.
The operational impact of CVE-2018-0175 poses significant risks to network infrastructure availability and integrity. Network administrators may experience unexpected device reboots, service interruptions, or complete system compromise when attackers exploit this vulnerability. The potential for privilege escalation means that successful exploitation could grant attackers full administrative control over the affected network device, enabling them to modify routing tables, disable security features, or establish persistent backdoors within the network infrastructure. This vulnerability particularly affects enterprise networks where LLDP is enabled by default for network discovery and management purposes, making it a prime target for adversaries seeking to gain control over critical network infrastructure components. The attack methodology aligns with techniques described in the MITRE ATT&CK framework under the T1068 (Exploitation for Privilege Escalation) and T1499 (Endpoint Denial of Service) tactics, demonstrating how format string vulnerabilities can serve as initial access vectors for broader network compromise operations.
Cisco has addressed this vulnerability through software updates and patches that implement proper input validation and sanitization for LLDP packet processing. Network administrators should prioritize applying the relevant security patches to all affected devices and consider implementing network segmentation controls to limit the attack surface. Additional mitigations include disabling LLDP on network interfaces where it is not required, implementing proper access controls to restrict physical access to network equipment, and monitoring for unusual LLDP packet patterns that may indicate exploitation attempts. The vulnerability serves as a reminder of the importance of robust input validation in network protocol implementations and highlights the critical need for security testing of network infrastructure software to prevent similar weaknesses from being exploited in production environments.