CVE-2025-20140 in IOS XE
Summary
by MITRE • 05/07/2025
A vulnerability in the Wireless Network Control daemon (wncd) of Cisco IOS XE Software for Wireless LAN Controllers (WLCs) could allow an unauthenticated, adjacent wireless attacker to cause a denial of service (DoS) condition.
This vulnerability is due to improper memory management. An attacker could exploit this vulnerability by sending a series of IPv6 network requests from an associated wireless IPv6 client to an affected device. To associate a client to a device, an attacker may first need to authenticate to the network, or associate freely in the case of a configured open network. A successful exploit could allow the attacker to cause the wncd process to consume available memory and eventually cause the device to stop responding, resulting in a DoS condition.
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Analysis
by VulDB Data Team • 08/01/2025
The vulnerability identified as CVE-2025-20140 represents a critical denial of service weakness within Cisco IOS XE Software for Wireless LAN Controllers, specifically affecting the Wireless Network Control daemon (wncd). This flaw exists in the memory management implementation of the wncd process, which governs wireless network operations and client associations within wireless infrastructure. The vulnerability is particularly concerning because it can be exploited by adjacent wireless attackers who do not require authentication to initiate malicious activity, making it accessible to anyone within radio range of the affected wireless network. The attack vector involves sending crafted IPv6 network requests from a wireless client that has either authenticated to the network or freely associated in the case of open networks, demonstrating how even minimal network access can translate into significant operational disruption.
The technical exploitation of this vulnerability stems from improper memory handling within the wncd daemon, which is responsible for managing wireless network control functions including client associations, authentication processes, and network configuration updates. When an attacker sends a series of IPv6 requests to the affected device, the wncd process fails to properly manage memory allocation and deallocation, leading to progressive memory consumption that eventually exhausts available system resources. This memory management flaw aligns with common software security weaknesses documented in CWE-401, which specifically addresses improper handling of memory allocation and deallocation. The vulnerability demonstrates how insufficient input validation and memory management controls can create conditions where legitimate network operations become vectors for resource exhaustion attacks, particularly when dealing with IPv6 protocols that introduce additional complexity in network request handling.
The operational impact of this vulnerability extends beyond simple service interruption, as it can effectively render entire wireless networks unavailable to legitimate users while potentially creating conditions that could be leveraged for more sophisticated attacks. When the wncd process consumes all available memory resources, the wireless controller becomes unresponsive and ceases to function properly, disrupting network connectivity for all associated wireless clients. This disruption can have cascading effects on business operations, particularly in enterprise environments where wireless networks support critical applications, communication systems, and network infrastructure. The vulnerability affects the fundamental availability of wireless services and can be particularly damaging in mission-critical environments where network uptime is essential for business continuity. From an attacker perspective, this represents a low-effort, high-impact vector that requires minimal privileges and can be executed from adjacent network positions, making it attractive for both opportunistic and targeted attacks.
Organizations affected by this vulnerability should prioritize immediate remediation through official Cisco security advisories and patches, as the memory management issues can be exploited to create persistent service disruptions. The vulnerability's adjacency requirement means that physical or wireless network proximity is necessary for exploitation, but this limitation does not mitigate the risk since wireless attackers can easily establish positions within network coverage areas. Network segmentation and access controls should be reviewed to minimize potential attack surfaces, while monitoring systems should be enhanced to detect unusual memory consumption patterns in wireless controllers. This vulnerability also highlights the importance of secure coding practices and memory management validation, particularly for network control daemons that handle critical infrastructure functions. The attack pattern aligns with techniques documented in the MITRE ATT&CK framework under the T1499 category for network denial of service, where adversaries seek to disrupt network availability through resource exhaustion and system instability. Organizations should consider implementing network monitoring solutions that can detect abnormal memory usage patterns and automated response mechanisms to mitigate the impact of such attacks before they can cause significant service disruption.