VulnerabilityPublished 4 Mar 2026

CVE-2026-20070: Cisco Secure Firewall Adaptive Security Appliance (ASA) Software · Basic XSS

Affects Cisco Secure Firewall Adaptive Security Appliance (ASA) SoftwareSource CVE Database V5

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Not known to be exploited · CVSS 6.1 Medium.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score

6.1Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.2% chance of exploitation in 30 days – higher than 20% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: Required
Scope: Changed
Confidentiality: Low
Integrity: Low
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 4 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
CiscoCisco Secure Firewall Adaptive Security Appliance (ASA) Software	Affected 9.12.1 – 9.23.1.19 161 affected builds	Fixed in–
CiscoCisco Secure Firewall Threat Defense (FTD) Software	Affected 6.4.0 – 7.7.10.1 75 affected builds	Fixed in–

AI-suggested

Apply official Cisco security patches and updates for ASA and FTD software as soon as they become available to address this vulnerability.
Restrict access to VPN web portals using network segmentation, IP whitelisting, or VPN gateway access controls to limit exposure to untrusted networks.
Implement strong input validation and output encoding on all web interfaces to prevent injection of malicious scripts.
Deploy Content Security Policy (CSP) headers on VPN web services to restrict execution of unauthorized scripts in browsers.
Educate users about phishing risks and the dangers of clicking unknown or suspicious links, especially those purporting to be VPN login pages.
Monitor VPN web server logs for unusual or suspicious HTTP requests that may indicate attempted exploitation.
Consider using multi-factor authentication (MFA) to reduce the impact of stolen credentials or session tokens.
Regularly review and update firewall and intrusion detection/prevention system (IDS/IPS) rules to detect and block XSS attack patterns targeting VPN portals.
Conduct periodic security assessments and penetration testing of VPN web services to identify and remediate input validation weaknesses.

Description

A vulnerability in the VPN web services component of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to conduct a cross-site scripting (XSS) attack against a browser that is accessing an affected device.  This vulnerability is due to improper validation of user-supplied input in HTTP requests. An attacker could exploit this vulnerability by persuading a user to follow a link to a malicious website that is designed to submit malicious input to the affected application. A successful exploit could allow the attacker to execute arbitrary HTML or script code in the browser in the context of the VPN web server.

Impact

The potential impact of CVE-2026-20070 is significant for organizations relying on Cisco Secure Firewall ASA and FTD VPN services for secure remote access. Successful exploitation can lead to execution of arbitrary scripts in users' browsers, enabling attackers to hijack VPN sessions, steal authentication tokens, or perform actions on behalf of the user. This compromises confidentiality and integrity of user sessions and potentially the broader network if attackers gain elevated access. Although availability is not directly impacted, the breach of trust and data exposure can lead to further attacks, including lateral movement within networks. Enterprises with large remote workforces or critical infrastructure protected by Cisco ASA/FTD VPNs face increased risk. The widespread use of affected versions means many organizations globally could be vulnerable if patches are not applied promptly. The requirement for user interaction (clicking a malicious link) somewhat limits exploitation but does not eliminate risk, especially in phishing-prone environments. The vulnerability could also be leveraged in targeted attacks against high-value individuals or organizations, increasing its strategic importance.

References

sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-webvpn-xss-uwjc4HR (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 4 Mar 2026, 18:33 UTC

Technical details

References

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