---
id: CVE-2020-3529
title: >-
  A vulnerability in the SSL VPN negotiation process for Cisco Adaptive Security
  Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software
  could allow an unauthenticated, remote attacker to cause a reload of an
  affected de…
summary: >-
  A vulnerability in the SSL VPN negotiation process for Cisco Adaptive Security
  Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software
  could allow an unauthenticated, remote attacker to cause a reload of an
  affected de…
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-400
  - CWE-400
vendor: cisco
product: adaptive_security_appliance
affected:
  - adaptive_security_appliance < 9.6.4.45
  - secure_firewall_threat_defense < 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, < 6.6.1'
  - 'adaptive_security_appliance_software >= 9.8.0, < 9.8.4.29'
  - '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, < 9.12.4.4'
  - 'adaptive_security_appliance_software >= 9.13.0, < 9.13.1.13'
  - 'adaptive_security_appliance_software >= 9.14.0, < 9.14.1.30'
patched:
  - adaptive_security_appliance 9.6.4.45
  - secure_firewall_threat_defense 6.6.1
  - adaptive_security_appliance_software 9.14.1.30
published: '2020-10-21'
updated: '2026-08-11'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2020-3529'
references:
  - url: >-
      https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-sslvpndma-dos-HRrqB9Yx
    label: psirt@cisco.com
  - url: >-
      https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-sslvpndma-dos-HRrqB9Yx
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
epss: 0.01855
epssPercentile: 0.78272
ingestedAt: '2026-08-11T19:48:28.642Z'
---

## Overview

A vulnerability in the SSL VPN negotiation process for Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a reload of an affected device, resulting in a denial of service (DoS) condition. The vulnerability is due to inefficient direct memory access (DMA) memory management during the negotiation phase of an SSL VPN connection. An attacker could exploit this vulnerability by sending a steady stream of crafted Datagram TLS (DTLS) traffic to an affected device. A successful exploit could allow the attacker to exhaust DMA memory on the device and cause a DoS condition.

## Affected

- `adaptive_security_appliance < 9.6.4.45`
- `secure_firewall_threat_defense < 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, < 6.6.1`
- `adaptive_security_appliance_software >= 9.8.0, < 9.8.4.29`
- `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, < 9.12.4.4`
- `adaptive_security_appliance_software >= 9.13.0, < 9.13.1.13`
- `adaptive_security_appliance_software >= 9.14.0, < 9.14.1.30`

## Remediation

Upgrade past the affected range:

- `adaptive_security_appliance 9.6.4.45`
- `secure_firewall_threat_defense 6.6.1`
- `adaptive_security_appliance_software 9.14.1.30`