CVE-2024-20354: Cisco Wireless LAN Controller DoS Vulnerability

CVE-2024-20354 Overview

CVE-2024-20354 is a denial of service (DoS) vulnerability in the wireless frame handling logic of Cisco Aironet Access Point (AP) Software. The flaw stems from incomplete cleanup of resources when the access point drops certain malformed encrypted wireless frames [CWE-460]. An unauthenticated attacker within wireless range can associate as a client and transmit crafted frames that progressively degrade service. Sustained exploitation can produce a complete denial of service for other wireless clients connected to the affected AP. Cisco disclosed the issue in the advisory cisco-sa-airo-ap-dos-PPPtcVW.

Critical Impact
An adjacent, unauthenticated attacker can cause service degradation or a complete DoS on affected Cisco Aironet access points, disrupting wireless connectivity for all associated clients.

Affected Products

Cisco Aironet Access Points: 1530e/i, 1552h/s/wu, 1700i, 2700e/i, 3700e/i/p
Cisco AP801, AP802, AP803, and IW3700 Industrial Wireless access points
Cisco Wireless LAN Controller Software and Cisco IOS XE running affected AP software

Discovery Timeline

2024-03-27 - CVE-2024-20354 published to NVD by Cisco Systems
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2024-20354

Vulnerability Analysis

The vulnerability resides in the frame-processing path that handles encrypted wireless frames on affected Cisco Aironet APs. When the AP encounters certain malformed frames, it drops them without fully releasing the internal resources allocated during parsing. Repeated delivery of these frames causes resource accumulation on the device. As internal buffers or tracking structures fill, the AP becomes unable to service legitimate client traffic. The condition first manifests as degraded throughput and connection issues for associated clients, then escalates toward a full denial of service.

Root Cause

The underlying weakness is classified as improper cleanup on thrown exception or error path [CWE-460]. The frame-drop routine terminates processing without invoking the corresponding resource release logic. Because the leak occurs on every malformed frame, an attacker controls the rate at which the AP exhausts its available resources.

Attack Vector

Exploitation requires wireless adjacency but no authentication or user interaction. The attacker associates to the target AP as a wireless client, then transmits a stream of specifically malformed encrypted frames. Each frame triggers the incomplete cleanup path, incrementally starving the AP of resources. No credentials, prior access, or victim interaction are needed. See the Cisco Security Advisory for vendor technical details.

Detection Methods for CVE-2024-20354

Indicators of Compromise

Unexpected client disassociation events and repeated authentication failures across a single AP.
AP-side logs indicating dropped malformed frames at abnormally high rates.
Progressive degradation of wireless throughput, followed by AP unresponsiveness or forced reboot.
Resource-exhaustion syslog messages from affected access points running Cisco IOS XE.

Detection Strategies

Baseline the volume of malformed frame drops per AP and alert on deviations from normal.
Correlate wireless client complaints with SNMP counters showing rising memory or buffer usage on the AP.
Monitor for a single wireless client MAC address transmitting sustained anomalous frame patterns before AP degradation.

Monitoring Recommendations

Ingest Cisco Wireless LAN Controller and AP syslog into a centralized SIEM or data lake for correlation.
Track AP CPU, memory, and reboot events per device and alert on repeated resets on the same AP.
Enable Wireless Intrusion Prevention System (wIPS) signatures for malformed 802.11 frames where available.

How to Mitigate CVE-2024-20354

Immediate Actions Required

Identify all Aironet APs and Wireless LAN Controllers in inventory that match the affected models listed in the Cisco advisory.
Apply the fixed Cisco AP software release referenced in cisco-sa-airo-ap-dos-PPPtcVW during the next maintenance window.
Restrict physical and RF exposure of affected APs where feasible, especially in high-density or externally accessible deployments.

Patch Information

Cisco has published fixed software releases in the Cisco Security Advisory cisco-sa-airo-ap-dos-PPPtcVW. Administrators should upgrade affected Aironet APs and any Wireless LAN Controllers managing them to the versions specified in the advisory. No workarounds are provided by Cisco; patching is the supported remediation path.

Workarounds

No vendor workarounds are available. Cisco explicitly recommends upgrading to a fixed software release.
Where patching cannot be completed immediately, reduce attack surface by disabling unused SSIDs and enforcing client authentication controls to limit adjacency.
Monitor AP health and be prepared to restart affected APs to temporarily restore service if exploitation is observed.

bash

# Example: verify running AP software version on a Cisco WLC / IOS XE controller
show ap image summary
show wireless summary
show version | include Version