Atomicorp WAF Research Note: CVE-2020-3580

Cisco ASA/FTD Software - Cross-Site Scripting

CVE Details

• Already protected by existing Atomicorp WAF rules
• Protection status: Understanding Atomicorp WAF Protection Status
• CVE: CVE-2020-3580
• Name: Cisco ASA/FTD Software - Cross-Site Scripting
• Severity: Medium
• CVSS: 6.1 (v3.1) (Medium)
• CVSS version: 3.1
• CVSS source: NVD
• CVSS vector: 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 impact: Low
  • Integrity impact: Low
  • Availability impact: None
• CWE: CWE-79 — Improper Neutralization of Input During Web Page Generation (‘Cross-site Scripting’)
• Related CAPEC attack patterns (via MITRE CWE relationships): CAPEC-209 (opens in a new tab) , CAPEC-588 (opens in a new tab) , CAPEC-591 (opens in a new tab) , CAPEC-592 (opens in a new tab) , CAPEC-63 (opens in a new tab) , CAPEC-85 (opens in a new tab)
• Vendor: cisco
• Vulnerable products: secure firewall threat defense , adaptive security appliance software , firepower threat defense
• CVE published: 2020-10-21
• CVE last modified: 2026-08-11
• Affected versions (NVD configurations):
  • secure firewall threat defense: < 6.4.0.12
  • secure firewall threat defense: >= 6.5.0, < 6.6.4
  • secure firewall threat defense: >= 6.7.0, < 6.7.0.2
  • adaptive security appliance software: < 9.8.4.34
  • adaptive security appliance software: >= 9.9, < 9.9.2.85
  • adaptive security appliance software: >= 9.10, < 9.12.4.13
  • adaptive security appliance software: >= 9.13, < 9.13.1.21
  • adaptive security appliance software: >= 9.14, < 9.14.2.8
  • adaptive security appliance software: >= 9.15, < 9.15.1.15
• EPSS: 0.8558; 99.7th percentile (FIRST (opens in a new tab) )
• CISA KEV: Listed (added 2021-11-03)
  • Known ransomware campaign use: Known
• Latest Update: 2026-09-06
• Selected Rule IDs observed: 333141 , 341256 , 342259 , 346755 , 350147 , 350148
• Matching rules: 6; rules with blocking actions: 6
• Would-block Rule IDs: 333141 , 341256 , 342259 , 346755 , 350147 , 350148
• Request surfaces inspected: JSON request data, Request URI, Request argument names, Request arguments, Request cookies, Request filename, Request headers, SOAP request data, XML request data

Vulnerability Description

Multiple vulnerabilities in the web services interface of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to conduct cross-site scripting (XSS) attacks against a user of the web services interface of an affected device. The vulnerabilities are due to insufficient validation of user-supplied input by the web services interface of an affected device. An attacker could exploit these vulnerabilities by persuading a user of the interface to click a crafted link. A successful exploit could allow the attacker to execute arbitrary script code in the context of the interface or allow the attacker to access sensitive, browser-based information. Note: These vulnerabilities affect only specific AnyConnect and WebVPN configurations. For more information, see the Vulnerable Products section.

Recommended Actions

1. Maintain the observed Atomicorp protections. Keep your Atomicorp commercial rules current and confirm that the selected observed rules (333141 , 341256 , 342259 , 346755 , 350147 , 350148 ) have not been locally disabled. Atomicorp commercial rules are enabled by default. If you use Atomic WAF, review the applicable policy and rule settings.

2. Apply the vendor’s remediation. WAF protection is defense in depth and does not replace upgrading or following the affected vendor’s guidance.

   • The CVE record does not include written upgrade or workaround instructions, but it does publish the following patch or mitigation reference:
     • Patch or mitigation information (opens in a new tab)
   • CISA KEV required action: Apply updates per vendor instructions.
   • CISA KEV federal remediation due date: 2022-05-03

3. Validate after changes. Confirm rule updates are current, review WAF events for the affected application, and test application behavior after vendor upgrades, mitigations, or local policy changes.

Research Notes

Atomicorp WAF protections are designed around attack techniques and exploit behaviors, allowing existing protections to apply across multiple vulnerabilities without requiring a unique rule for every CVE.

Public Vulnerability References

• NVD (opens in a new tab)
• CVE Record (opens in a new tab)
• Vendor advisory: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-xss-multiple-FCB3vPZe (opens in a new tab)
• CVE authority reference: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-3580 (opens in a new tab)

MITRE ATT&CK Context

The following mappings are published by the MITRE Center for Threat-Informed Defense and describe exploitation behavior or potential impact; they do not claim that a WAF rule implements the ATT&CK technique.

• Secondary Impact: T1217 — Browser Information Discovery (opens in a new tab)
• Primary Impact: T1059 — Command and Scripting Interpreter (opens in a new tab)
• Exploitation Technique: T1204.001 — Malicious Link (opens in a new tab)

Test or Research Source

• Source: http/cves/2020/CVE-2020-3580.yaml (opens in a new tab)
• Tags: cisco, cve, cve2020, kev, vkev, vuln, xss

Research Note Context

This research note documents exploit-technique analysis associated with this vulnerability and references Atomicorp WAF protections observed during engineering review, testing, or validation activities.

Atomicorp security controls are generally designed to identify and mitigate attack techniques and exploit behaviors rather than individual CVE identifiers. As a result, protections developed for one vulnerability may also apply to related attack variants and future vulnerabilities using similar techniques.

Learn More

Atomicorp develops commercially supported security technologies for web applications, servers, endpoints, workloads, and legacy enterprise platforms.

Organizations interested in protecting systems against exploit techniques associated with vulnerabilities such as this one can learn more about:

• Atomic ModSecurity Rules: commercially maintained WAF rules for ModSecurity deployments, including protections for web attacks, bots, scanners, malware, exploitation attempts, and emerging vulnerability classes.
• Atomic WAF: an enterprise web application firewall with Atomicorp rules, centralized management, reporting, authentication controls, and operational tooling.
• Atomic ModSecurity Integrator: a special licensing option for MSPs, MSSPs, OEMs, VARs, reverse proxy providers, and other integrators who want to incorporate Atomicorp ModSecurity rule technology into their own products or services.
• Atomic OSSEC: an enterprise OSSEC-based intrusion detection, compliance, and security monitoring platform.
• Atomic Protector: workload protection for Linux, web, cloud, data center, and hybrid environments.

For additional information, product evaluations, or technical discussions, visit https://www.atomicorp.com/ or https://modsecurity.io/ (opens in a new tab) .