---
id: CVE-2020-3436
title: >-
  A vulnerability in the web services interface of Cisco Adaptive Security
  Appliance (ASA) and Cisco Firepower Threat Defense (FTD) Software could allow
  an unauthenticated, remote attacker to upload arbitrary-sized files to
  specific folder…
summary: >-
  A vulnerability in the web services interface of Cisco Adaptive Security
  Appliance (ASA) and Cisco Firepower Threat Defense (FTD) Software could allow
  an unauthenticated, remote attacker to upload arbitrary-sized files to
  specific folder…
severity: high
cvss: 8.6
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H'
cwe:
  - CWE-434
  - CWE-434
vendor: cisco
product: adaptive_security_appliance
affected:
  - adaptive_security_appliance < 9.6.4.45
  - secure_firewall_threat_defense <= 6.2.2
  - 'secure_firewall_threat_defense >= 6.3.0, < 6.3.0.6'
  - 'secure_firewall_threat_defense >= 6.4.0, < 6.4.0.10'
  - 'secure_firewall_threat_defense >= 6.5.0, < 6.5.0.5'
  - secure_firewall_threat_defense = 6.6.0
  - 'adaptive_security_appliance_software >= 9.8.0, < 9.8.4.25'
  - 'adaptive_security_appliance_software >= 9.9.0, < 9.9.2.80'
  - 'adaptive_security_appliance_software >= 9.10.0, < 9.10.1.44'
  - 'adaptive_security_appliance_software >= 9.12.0, < 9.12.4.2'
  - 'adaptive_security_appliance_software >= 9.13.0, < 9.13.1.12'
  - 'adaptive_security_appliance_software >= 9.14.0, < 9.14.1.15'
patched:
  - adaptive_security_appliance 9.6.4.45
  - secure_firewall_threat_defense 6.5.0.5
  - adaptive_security_appliance_software 9.14.1.15
published: '2020-10-21'
updated: '2026-08-11'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2020-3436'
references:
  - url: >-
      https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-fileup-dos-zvC7wtys
    label: psirt@cisco.com
  - url: >-
      https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-fileup-dos-zvC7wtys
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
epss: 0.01935
epssPercentile: 0.79195
ingestedAt: '2026-08-11T19:48:28.510Z'
---

## Overview

A vulnerability in the web services interface of Cisco Adaptive Security Appliance (ASA) and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to upload arbitrary-sized files to specific folders on an affected device, which could lead to an unexpected device reload. The vulnerability exists because the affected software does not efficiently handle the writing of large files to specific folders on the local file system. An attacker could exploit this vulnerability by uploading files to those specific folders. A successful exploit could allow the attacker to write a file that triggers a watchdog timeout, which would cause the device to unexpectedly reload, causing a denial of service (DoS) condition.

## Affected

- `adaptive_security_appliance < 9.6.4.45`
- `secure_firewall_threat_defense <= 6.2.2`
- `secure_firewall_threat_defense >= 6.3.0, < 6.3.0.6`
- `secure_firewall_threat_defense >= 6.4.0, < 6.4.0.10`
- `secure_firewall_threat_defense >= 6.5.0, < 6.5.0.5`
- `secure_firewall_threat_defense = 6.6.0`
- `adaptive_security_appliance_software >= 9.8.0, < 9.8.4.25`
- `adaptive_security_appliance_software >= 9.9.0, < 9.9.2.80`
- `adaptive_security_appliance_software >= 9.10.0, < 9.10.1.44`
- `adaptive_security_appliance_software >= 9.12.0, < 9.12.4.2`
- `adaptive_security_appliance_software >= 9.13.0, < 9.13.1.12`
- `adaptive_security_appliance_software >= 9.14.0, < 9.14.1.15`

## Remediation

Upgrade past the affected range:

- `adaptive_security_appliance 9.6.4.45`
- `secure_firewall_threat_defense 6.5.0.5`
- `adaptive_security_appliance_software 9.14.1.15`