CVE-2019-1826 in Aironet
Summary
by MITRE
A vulnerability in the quality of service (QoS) feature of Cisco Aironet Series Access Points (APs) could allow an authenticated, adjacent attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to improper input validation on QoS fields within Wi-Fi frames by the affected device. An attacker could exploit this vulnerability by sending malformed Wi-Fi frames to an affected device. A successful exploit could allow the attacker to cause the affected device to crash, resulting in a DoS condition.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 09/04/2023
The vulnerability identified as CVE-2019-1826 resides within the quality of service implementation of Cisco Aironet Series Access Points, representing a critical security weakness that compromises network availability. This flaw specifically targets the QoS feature which governs traffic prioritization and bandwidth allocation in wireless networks. The affected devices operate under the assumption that incoming Wi-Fi frames containing QoS parameters will conform to expected formats and values, creating an attack surface where malformed data can disrupt normal operations.
The technical root cause of this vulnerability stems from inadequate input validation mechanisms within the wireless access point firmware. When processing Wi-Fi frames that contain QoS fields, the affected Cisco Aironet APs fail to properly validate the structure and content of these fields before attempting to process them. This validation gap allows an attacker to craft specially formatted frames that contain malformed QoS parameters, which when received by the vulnerable device trigger unexpected behavior in the processing pipeline. The improper input validation creates a condition where the device's QoS handling code encounters unexpected data structures that it cannot properly interpret or manage, leading to system instability.
The operational impact of this vulnerability manifests as a denial of service condition that can completely disrupt wireless network operations within the affected access point's coverage area. An authenticated attacker positioned within the wireless range of the vulnerable device can exploit this weakness by transmitting carefully crafted malformed Wi-Fi frames that target the QoS processing functionality. Upon receiving these malicious frames, the affected access point experiences a crash or reboot cycle, effectively removing wireless connectivity for all connected clients within that coverage zone. This disruption can have cascading effects on network availability, particularly in enterprise environments where wireless infrastructure supports critical business operations.
The exploitation of CVE-2019-1826 aligns with ATT&CK technique T1499.001 for network denial of service attacks and demonstrates characteristics consistent with CWE-20 input validation errors. This vulnerability represents a classic example of how insufficient validation of network protocol elements can lead to system compromise, particularly in wireless infrastructure devices where network traffic processing is critical to service delivery. The adjacent attack vector requirement means that physical proximity to the target device is necessary for exploitation, limiting the attack scope but not eliminating the potential for significant disruption in environments where wireless access points are strategically positioned throughout facilities.
Organizations should implement immediate mitigations including firmware updates from Cisco to address the input validation deficiencies in the QoS processing code. Network administrators should also consider implementing additional monitoring for unusual frame patterns that may indicate exploitation attempts, particularly focusing on QoS-related Wi-Fi frames. The vulnerability underscores the importance of validating all network input at multiple layers of the protocol stack and demonstrates why robust input validation should be a fundamental security control in wireless infrastructure devices. Security teams should also review their wireless network configurations to ensure that access point authentication mechanisms are properly enforced to limit unauthorized access to the wireless network and reduce the risk of exploitation.