---
id: CVE-2021-1256
title: >-
  A vulnerability in the CLI of Cisco Firepower Threat Defense (FTD) Software
  could allow an authenticated, local attacker to overwrite files on the file
  system of an affected device by using directory traversal techniques
summary: >-
  A vulnerability in the CLI of Cisco Firepower Threat Defense (FTD) Software
  could allow an authenticated, local attacker to overwrite files on the file
  system of an affected device by using directory traversal techniques. A
  successful ex…
severity: medium
cvss: 6
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:H'
cwe:
  - CWE-552
  - CWE-22
  - CWE-552
vendor: cisco
product: secure_firewall_threat_defense
affected:
  - secure_firewall_threat_defense <= 6.4.0
  - 'secure_firewall_threat_defense >= 6.6.0, < 6.6.4'
patched:
  - secure_firewall_threat_defense 6.6.4
published: '2021-04-29'
updated: '2026-08-11'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2021-1256'
references:
  - url: 'https://kc.mcafee.com/corporate/index?page=content&id=SB10382'
    label: psirt@cisco.com
  - url: >-
      https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-file-overwrite-XknRjGdB
    label: psirt@cisco.com
  - url: 'https://kc.mcafee.com/corporate/index?page=content&id=SB10382'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-file-overwrite-XknRjGdB
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
epss: 0.00497
epssPercentile: 0.4171
ingestedAt: '2026-08-18T12:28:06.913Z'
---

## Overview

A vulnerability in the CLI of Cisco Firepower Threat Defense (FTD) Software could allow an authenticated, local attacker to overwrite files on the file system of an affected device by using directory traversal techniques. A successful exploit could cause system instability if important system files are overwritten. This vulnerability is due to insufficient validation of user input for the file path in a specific CLI command. An attacker could exploit this vulnerability by logging in to a targeted device and issuing a specific CLI command with crafted user input. A successful exploit could allow the attacker to overwrite arbitrary files on the file system of the affected device. The attacker would need valid user credentials on the device.

## Affected

- `secure_firewall_threat_defense <= 6.4.0`
- `secure_firewall_threat_defense >= 6.6.0, < 6.6.4`

## Remediation

Upgrade past the affected range:

- `secure_firewall_threat_defense 6.6.4`