Cisco IOS XE Software for Catalyst 9800 Series and Cisco AireOS Software for Cisco WLC Flexible NetFlow Version 9 Denial of Service Vulnerability

published 2020-09-24 6 y ago modified 2026-06-17 4 mo ago also EUVD-2020-24763

cvss: 8.6; version 3.0, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 1.4%; EPSS 1.4% chance of exploitation in 30 days, percentile 72%
public exploits: 0; none known

A vulnerability in the Flexible NetFlow Version 9 packet processor of Cisco IOS XE Software for Cisco Catalyst 9800 Series Wireless Controllers and Cisco AireOS Software for Cisco Wireless LAN Controllers (WLC) could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to insufficient validation of certain parameters in a Flexible NetFlow Version 9 record. An attacker could exploit this vulnerability by spoofing the address of an existing Access Point on the network and sending a Control and Provisioning of Wireless Access Points (CAPWAP) packet that includes a crafted Flexible NetFlow Version 9 record to an affected device. A successful exploit could allow the attacker to cause a process crash that would lead to a reload of the device.

CISA SSVC

Exploitation: none
Automatable: yes
Technical impact: partial
Assessed: 23 mo ago (2024-11-13)

Exploit prediction

1.37% chance of exploitation in the next 30 days, higher than 72% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.0	8.6	CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
NVD	3.1	8.6	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
NVD	2.0	7.8	AV:N/AC:L/Au:N/C:N/I:N/A:C

Affected products

Cisco Cisco Wireless LAN Controller (WLC)

Classification

Weakness

CWE-20 Improper Input Validation

Technology feeds

Cisco IOS rss critical rss

References

tools.cisco.com /security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxe-wlc-fnfv9-EvrAQpNX
vendor-advisory

Sources

CVE List CVE-2020-3492
NVD CVE-2020-3492

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary