CVE-2026-20103:

A vulnerability in Cisco Secure Firewall ASA and FTD Software allows unauthenticated remote attackers to cause denial of service in Remote Access SSL VPN functionality.

Score
A numerical rating that indicates how dangerous this vulnerability is.

8.6High

Published Date:Mar 4, 2026
CISA KEV Date:*No Data*
Industries Affected:20

Exploitability

Score:3.9
Attack Vector:NETWORK
Attack Complexity:LOW
Privileges Required:NONE
User Interaction:NONE
Scope:CHANGED

Impact

Score:4.0
Confidentiality Impact:NONE
Integrity Impact:NONE
Availability Impact:HIGH

Description Preview

A vulnerability in Cisco Secure Firewall ASA and FTD Software allows unauthenticated remote attackers to cause denial of service in Remote Access SSL VPN functionality.

Overview

The vulnerability stems from the software trusting user input without proper validation. An attacker can exploit this by sending crafted packets to the Remote Access SSL VPN server, potentially causing the device web interface to stop responding. This creates a DoS condition, impacting the availability of the VPN service. The vulnerability has a CVSS v3.1 base score of 8.6, categorized as HIGH severity. It is characterized by network-based attack vector, low attack complexity, and no required privileges or user interaction. While the confidentiality and integrity impacts are none, the availability impact is high, with the scope being changed.

Remediation

To address this vulnerability, organizations using affected Cisco Secure Firewall ASA and FTD Software should:
1. Apply the latest security updates provided by Cisco as soon as they become available.
2. Implement network segmentation and access controls to limit exposure of the affected systems.
3. Monitor systems for unusual activity, particularly targeting the Remote Access SSL VPN functionality.
4. Consider implementing additional security measures such as intrusion detection and prevention systems to detect and block potential exploit attempts.
5. Regularly review and update security configurations and access policies for the affected devices.