---
id: CVE-2020-3166
title: >-
  A vulnerability in the CLI of Cisco FXOS Software could allow an
  authenticated, local attacker to read or write arbitrary files on the
  underlying operating system (OS)
summary: >-
  A vulnerability in the CLI of Cisco FXOS Software could allow an
  authenticated, local attacker to read or write arbitrary files on the
  underlying operating system (OS). The vulnerability is due to insufficient
  input validation. An attack…
severity: medium
cvss: 6.7
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-20
  - CWE-20
vendor: cisco
product: secure_firewall_threat_defense
affected:
  - 'secure_firewall_threat_defense >= 6.2.2, < 6.2.3.16'
  - 'secure_firewall_threat_defense >= 6.3.0, < 6.5.0.3'
  - 'adaptive_security_appliance_software >= 9.8, < 9.9.2.66'
  - 'adaptive_security_appliance_software >= 9.10, < 9.13.1.5'
  - firepower_extensible_operating_system < 2.2.2.97
  - 'firepower_extensible_operating_system >= 2.3, < 2.3.1.155'
  - 'firepower_extensible_operating_system >= 2.4, < 2.4.1.238'
  - 'firepower_extensible_operating_system >= 2.6, < 2.6.1.157'
patched:
  - secure_firewall_threat_defense 6.5.0.3
  - adaptive_security_appliance_software 9.13.1.5
  - firepower_extensible_operating_system 2.6.1.157
published: '2020-02-26'
updated: '2026-08-11'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2020-3166'
references:
  - url: >-
      https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20200226-fxos-cli-file
    label: psirt@cisco.com
  - url: >-
      https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20200226-fxos-cli-file
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
epss: 0.00285
epssPercentile: 0.21249
ingestedAt: '2026-08-11T19:48:27.310Z'
---

## Overview

A vulnerability in the CLI of Cisco FXOS Software could allow an authenticated, local attacker to read or write arbitrary files on the underlying operating system (OS). The vulnerability is due to insufficient input validation. An attacker could exploit this vulnerability by including crafted arguments to a specific CLI command. A successful exploit could allow the attacker to read or write to arbitrary files on the underlying OS.

## Affected

- `secure_firewall_threat_defense >= 6.2.2, < 6.2.3.16`
- `secure_firewall_threat_defense >= 6.3.0, < 6.5.0.3`
- `adaptive_security_appliance_software >= 9.8, < 9.9.2.66`
- `adaptive_security_appliance_software >= 9.10, < 9.13.1.5`
- `firepower_extensible_operating_system < 2.2.2.97`
- `firepower_extensible_operating_system >= 2.3, < 2.3.1.155`
- `firepower_extensible_operating_system >= 2.4, < 2.4.1.238`
- `firepower_extensible_operating_system >= 2.6, < 2.6.1.157`

## Remediation

Upgrade past the affected range:

- `secure_firewall_threat_defense 6.5.0.3`
- `adaptive_security_appliance_software 9.13.1.5`
- `firepower_extensible_operating_system 2.6.1.157`