Security Resilience

CVE-2020-3580

XSS in Cisco Adaptive Security Appliance Software ≤ 9.8.4.34

CISA KEVActive ExploitationEUVD ExploitedRansomware-linkedXSS
Published
21 October 2020
Modified
11 August 2026
KEV Added
03 November 2021
Patch / advisory
View advisory
CVSS Score v3.1 6.1
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
EPSS Score 0.86 99.7th percentile
Risk Priority 75 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2020-3580 is a medium-severity Cross-site Scripting (CWE-79) vulnerability in Cisco Adaptive Security Appliance Software. Its CVSS base score is 6.1 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Protocol or Service Impersonation (T1001.003); ranked in the top 0.3% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

Multiple vulnerabilities in the web services interface of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow cross-site scripting attacks. The issues stem from insufficient validation of user-supplied input and affect only specific AnyConnect and WebVPN configurations on those products.

An unauthenticated remote attacker can exploit the flaws by persuading a user of the interface to click a crafted link. Successful exploitation enables execution of arbitrary script code in the context of the interface or access to sensitive browser-based information.

The Cisco Security Advisory cisco-sa-asaftd-xss-multiple-FCB3vPZe provides details on affected versions and recommended mitigations. CVE-2020-3580 is listed in the CISA Known Exploited Vulnerabilities Catalog, confirming observed in-the-wild exploitation.

OWASP Top 10 for Web (2025)

A05:2025 Injection

EU & UK References

Vulnerability Data

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…

more

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.

CWE(s)
CWE-79
KEV Date Added
03 November 2021

Related Threats

Threat-Actor AttributionAI

Amazon.com (Walmart logistics engineer recruitment civil claims)
#StopRansomware: Akira Ransomware | CISA
Cloudflare (Akamai trade-secret civil claims)
#StopRansomware: Akira Ransomware | CISA
CrowdStrike (McAfee / Symantec civil claims)
#StopRansomware: Akira Ransomware | CISA
Google LLC (civil insider-recruitment defendant)
#StopRansomware: Akira Ransomware | CISA
Microsoft Corp. (Salesforce / Slack engineer recruitment claims)
#StopRansomware: Akira Ransomware | CISA
Akira (G1024)
#StopRansomware: Akira Ransomware | CISA
AnonOps
#StopRansomware: Akira Ransomware | CISA
l group
#StopRansomware: Akira Ransomware | CISA

MITRE ATT&CK Enterprise Techniques

T1001.003 Protocol or Service Impersonation Command And Control
Adversaries may impersonate legitimate protocols or web service traffic to disguise command and control activity and thwart analysis efforts.
attack.mitre.org →
T1003.004 LSA Secrets Credential Access
Adversaries with SYSTEM access to a host may attempt to access Local Security Authority (LSA) secrets, which can contain a variety of different credential materials, such as credentials for service accounts.
attack.mitre.org →
T1003.005 Cached Domain Credentials Credential Access
Adversaries may attempt to access cached domain credentials used to allow authentication to occur in the event a domain controller is unavailable.
attack.mitre.org →
T1007 System Service Discovery Discovery
Adversaries may try to gather information about registered local system services.
attack.mitre.org →
T1011 Exfiltration Over Other Network Medium Exfiltration
Adversaries may attempt to exfiltrate data over a different network medium than the command and control channel.
attack.mitre.org →
T1012 Query Registry Discovery
Adversaries may interact with the Windows Registry to gather information about the system, configuration, and installed software.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2014-2120Same product: Cisco Adaptive Security Appliance Softwareboth on KEV
CVE-2023-20096Same vendor: Cisco
CVE-2023-20068Same vendor: Cisco
CVE-2023-20149Same vendor: Cisco
CVE-2023-20141Same vendor: Cisco
CVE-2023-20028Same vendor: Cisco
CVE-2023-20145Same vendor: Cisco
CVE-2023-20085Same vendor: Cisco
CVE-2023-20146Same vendor: Cisco
CVE-2023-20137Same vendor: Cisco

Affected Assets

cisco
secure firewall threat defense
≤ 6.4.0.12 · 6.5.0 — 6.6.4 · 6.7.0 — 6.7.0.2
cisco
adaptive security appliance software
≤ 9.8.4.34 · 9.9 — 9.9.2.85 · 9.10 — 9.12.4.13

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V1.1.2
  • V1.3.2

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

CA-8 Penetration Testing
addresses: CWE-79

Penetration testing submits XSS payloads to web applications, detecting cross-site scripting flaws for subsequent remediation.

SI-10 Information Input Validation
addresses: CWE-79

Validates web inputs to reject script-related content that could produce XSS.

SI-15 Information Output Filtering
addresses: CWE-79

Output validation against expected content can reject or sanitize script content in generated web pages, reducing XSS exploitability.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
blocks

Secure SDLC practices directly target introduction of XSS via coding standards/testing (mostly), yet the single broad outcome leaves many specific neutralization vectors unaddressed (partial).

PR.PS-02 partial match
blocks

Patching and EOL replacement can remediate known XSS instances in libraries or frameworks (partial) but do nothing to enforce input neutralization in application code (none).

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.5.14 Information transfer partial match
removes
A.5.15 Access control partial match
removes
A.5.16 Identity management partial match
removes
A.5.17 Authentication information partial match
removes
A.5.18 Access rights partial match
removes
A.5.6 Contact with special interest groups partial match
blocks

A.5.6 only promotes membership in groups to improve knowledge, receive alerts, and share information; it performs no action that stops XSS exploitation (or even the underlying neutralization defect) and is a pure dependency for other controls per the owner's labeling rule.

References