CVE-2021-1437: Cisco Aironet Access Points FlexConnect Upgrade Information Disclosure Vulnerability

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-03-24 · updated 2026-06-17
Weakness: CWE-275

Description

A vulnerability in the FlexConnect Upgrade feature of Cisco Aironet Series Access Points Software could allow an unauthenticated, remote attacker to obtain confidential information from an affected device. This vulnerability is due to an unrestricted Trivial File Transfer Protocol (TFTP) configuration. An attacker could exploit this vulnerability by sending a specific TFTP request to an affected device. A successful exploit could allow the attacker to download any file from the filesystem of the affected access point (AP).

Affected products

Cisco Mobility Express 1800 Access Point Series: all versions
Cisco Catalyst 9800 Firmware: from 17.1 before 17.3.3 — fixed in 17.3.3
Cisco Wireless LAN Controller (WLC): from 8.10.112.0 before 8.10.142.0 — fixed in 8.10.142.0

How to fix

Upgrade to a fixed version: Cisco Catalyst 9800 Firmware 17.3.3; Cisco Wireless LAN Controller (WLC) 8.10.142.0. Check the vendor advisory for mitigations.

References

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