Cross-Site Scripting in Cisco ASA and FTD VPN Web Services

Executive Summary

[{'type': 'paragraph', 'content': 'CVE-2026-20070 is a medium-severity cross-site scripting (XSS) vulnerability affecting the VPN web services component of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software.'}, {'type': 'paragraph', 'content': 'The vulnerability occurs because the software improperly validates user-supplied input in HTTP requests. An unauthenticated, remote attacker can exploit this by convincing a user to visit a malicious website that submits crafted input to the vulnerable application.'}, {'type': 'paragraph', 'content': "If successfully exploited, the attacker can execute arbitrary HTML or script code in the victim's browser within the context of the VPN web server, potentially compromising the confidentiality and integrity of data handled by the VPN web services."}] [1]

Useful 0 Not Useful 0

Detection Guidance

This vulnerability can be detected by checking if the affected features are enabled on your Cisco Secure Firewall ASA or FTD devices.

• Use the command `show running-config` in the device CLI to verify if either Internet Key Exchange Version 2 (IKEv2) Remote Access VPN with client services enabled (`crypto ikev2 enable client-services port`) or SSL VPN (`webvpn enable`) features are active.

If these features are enabled, the device may be vulnerable to this cross-site scripting issue.

Useful 0 Not Useful 0

Impact Analysis

[{'type': 'paragraph', 'content': "This vulnerability can allow an attacker to execute arbitrary scripts in the context of a user's browser session when accessing the affected VPN web services."}, {'type': 'paragraph', 'content': "Such script execution can lead to compromise of confidentiality and integrity of data handled by the VPN web services, potentially exposing sensitive information or allowing unauthorized actions within the user's session."}, {'type': 'paragraph', 'content': 'Because the attack requires user interaction (the user must be persuaded to visit a malicious website), it can be used as part of targeted phishing or social engineering attacks.'}] [1]

Useful 0 Not Useful 0

Compliance Impact

I don't know

Useful 0 Not Useful 0

Mitigation Strategies

There are no available workarounds for this vulnerability.

The immediate and recommended step is to upgrade to the fixed software versions released by Cisco to remediate this issue.

Use the Cisco Software Checker tool to identify affected software versions and obtain the appropriate fixed releases.

Follow Cisco’s upgrade guides carefully to ensure hardware and software compatibility during the upgrade process.

If needed, consult Cisco TAC for additional support.

Useful 0 Not Useful 0