---
id: CVE-2020-3253
title: >-
  A vulnerability in the support tunnel feature of Cisco Firepower Threat
  Defense (FTD) Software could allow an authenticated, local attacker to access
  the shell of an affected device even though expert mode is disabled
summary: >-
  A vulnerability in the support tunnel feature of Cisco Firepower Threat
  Defense (FTD) Software could allow an authenticated, local attacker to access
  the shell of an affected device even though expert mode is disabled. The
  vulnerability …
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-284
vendor: cisco
product: secure_firewall_threat_defense
affected:
  - secure_firewall_threat_defense < 6.5.0
patched:
  - secure_firewall_threat_defense 6.5.0
published: '2020-05-06'
updated: '2026-08-11'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2020-3253'
references:
  - url: >-
      https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-shell-9rhJF68K
    label: psirt@cisco.com
  - url: >-
      https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-shell-9rhJF68K
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
epss: 0.00304
epssPercentile: 0.206
ingestedAt: '2026-08-11T19:48:27.648Z'
---

## Overview

A vulnerability in the support tunnel feature of Cisco Firepower Threat Defense (FTD) Software could allow an authenticated, local attacker to access the shell of an affected device even though expert mode is disabled. The vulnerability is due to improper configuration of the support tunnel feature. An attacker could exploit this vulnerability by enabling the support tunnel, setting a key, and deriving the tunnel password. A successful exploit could allow the attacker to run any system command with root access on an affected device.

## Affected

- `secure_firewall_threat_defense < 6.5.0`

## Remediation

Upgrade past the affected range:

- `secure_firewall_threat_defense 6.5.0`