CVE-2021-34740: Cisco Aironet Access Points WLAN Control Protocol Packet Buffer Leak Denial of Service Vulnerability

Severity: high (CVSS 7.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-09-23 · updated 2026-06-17
Weakness: CWE-401

Description

A vulnerability in the WLAN Control Protocol (WCP) implementation for Cisco Aironet Access Point (AP) software could allow an unauthenticated, adjacent attacker to cause a reload of an affected device, resulting in a denial of service (DoS) condition. This vulnerability is due to incorrect error handling when an affected device receives an unexpected 802.11 frame. An attacker could exploit this vulnerability by sending certain 802.11 frames over the wireless network to an interface on an affected AP. A successful exploit could allow the attacker to cause a packet buffer leak. This could eventually result in buffer allocation failures, which would trigger a reload of the affected device.

Affected products

Cisco Mobility Express 1800 Access Point Series: from 8.10.0 before 8.10.162.0; 17.2, 17.3 — fixed in 8.10.162.0

How to fix

Upgrade to a fixed version: Cisco Mobility Express 1800 Access Point Series 8.10.162.0. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2021-34740 or the next vulnerability affects your stack