Cisco IOS XE Wireless Controller Software for the Catalyst 9000 Family CAPWAP Denial of Service Vulnerabilities

Vulnerability

The vulnerability resides in the Control and Provisioning of Wireless Access Points (CAPWAP) protocol processing of Cisco IOS XE Software running on Cisco Catalyst 9800 Series Wireless Controllers. Due to insufficient validation of CAPWAP packets, an unauthenticated adjacent attacker can trigger a denial of service condition. Affected versions include various releases of Cisco IOS XE Software for the Catalyst 9800 series; refer to the Cisco advisory [1] for the complete list.

Exploitation

An attacker must be in the same Layer 2 network (adjacent) to send a malformed CAPWAP packet to the affected device. No authentication or user interaction is required. The attacker crafts a specially crafted CAPWAP packet and transmits it to the target controller, exploiting the insufficient validation.

Impact

Successful exploitation causes the affected device to crash and reload, resulting in a denial of service (DoS) condition. The device becomes unavailable until the reload completes, disrupting wireless services managed by the controller.

Mitigation

Cisco has released free software updates to address these vulnerabilities [1]. Customers should upgrade to the fixed software version as specified in the Cisco Security Advisory. No workarounds are mentioned; the recommended mitigation is to apply the patch. If upgrading is not immediately possible, consider restricting CAPWAP traffic to trusted sources as a temporary measure, though this may not fully mitigate the vulnerability.