BlackTreeCVE Intelligence
← Back to the CVE catalogue
Full vulnerability report · 2020
CVE-2020-3580High confidence

Cisco ASA and FTD Cross-Site Scripting (XSS) Vulnerability

Cisco · Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD)

Official source article: Cisco CISCO-SA-ASAFTD-XSS-MULTIPLE-FCB3VPZE ↗. Check the applicable product and release in the original source.

6.1MediumCVSS 3.1
Recommended action
Patch now

CISA confirms exploitation in the wild and lists 2022-05-03 as the remediation due date.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityMediumOperational priority:Critical, raised 2 bands.upgradedsince 3 Nov 2021

Evidence used

  • CISA confirms exploitation in the wild.
  • EPSS is 85.58% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict the affected network interface to trusted sources where business-safe.
  • Increase monitoring for the attack path and post-exploitation behaviour described in the report.

Verification

  1. Confirm that the asset runs Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: Within 3 daysRemediation target: Within 90 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2020-24851

CISA KEV mirrored by ENISA

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.

EUVD state
Present in the current official mapping
Known exploitation
Recorded by ENISA since 3 Nov 2021. Evidence sources: cisa_kev.
ENISA score
6.1 · CVSS 3.1
Advisory evidence
1 linked advisory record
Recommended actionPatch now

CISA confirms exploitation in the wild and lists 2022-05-03 as the remediation due date.

Patch available
01

What, why and how

Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) contain an insufficient input validation vulnerability for user-supplied input by the web services interface. Successful exploitation could allow an attacker to perform cross-site scripting (XSS) in the context of the interface or access sensitive browser-based information.

What

Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) contain an insufficient input validation vulnerability for user-supplied input by the web services interface. Successful exploitation could allow an attacker to perform cross-site scripting (XSS) in the context of the interface or access sensitive browser-based information.

Why

Attacker-controlled content can reach a browser as executable script without sufficient output encoding or sanitisation.

How

An attacker operating through a network path may attempt exploitation without authentication after a user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) contain an insufficient input validation vulnerability for user-supplied input by the web services interface. Successful exploitation could allow an attacker to perform cross-site scripting (XSS) in the context of the interface or access sensitive browser-based information.

Why

Attacker-controlled content can reach a browser as executable script without sufficient output encoding or sanitisation.

How

An attacker operating through a network path may attempt exploitation without authentication after a user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
Confirmed in the wild

CISA added this CVE to its Known Exploited Vulnerabilities catalogue on 2021-11-03. Known ransomware campaign use is recorded.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
a network path → Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
Required interaction required
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Changed: exploitation can affect a different security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-79 ↗

CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'). The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UIRequiredUser interaction: Another user must perform an action for exploitation to succeed.SChangedScope: The attack can affect a component governed by a different security authority.CLowConfidentiality impact: A successful attack can cause a limited loss.ILowIntegrity impact: A successful attack can cause a limited loss.ANoneAvailability impact: No direct loss is represented by this metric.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkUnauthenticatedCWE-79CISA KEV
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

ENISA EUVD · EUVD-2020-24851Known-exploited evidence recorded

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.

Official EUVD record ↗
Cyber Security Agency of Singapore · English · CSA-SB-20201028Security Bulletin 28 Oct 2020

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 28 Oct 2020, published on 28 October 2020. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2020-012620Cisco Adaptive Security Appliance および Cisco Firepower Threat Defense ソフトウェアにおけるクロスサイトスクリプティングの脆弱性

Cisco Adaptive Security Appliance (ASA) および Cisco Firepower Threat Defense (FTD) ソフトウェアには、クロスサイトスクリプティングの脆弱性が存在します。

Official advisory ↗
KISA KrCERT/CC · Korean · KNVD-5320Cisco ASA 및 FTD 제품 보안 업데이트 권고

Cisco ASA(Adaptive Security Appliance) 및 FTD(firepower Threat Defense)의 웹 인터페이스에서 입력값 검증이 미흡하여 발생하는 XSS 취약점(CVE-2020-3580, 3581, 3582, 3583) [1]

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Patch available
Affected
Cisco Adaptive Security Appliance (ASA) Software: n/a
Fixed
An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
Action
Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 21 Oct 2020 · Last source change 21 Oct 2025, 23:35 UTC · CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

CVE recordCVE.org · 5.1
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2020-24851
Product sourceCISA KEV
Remediation sourceCVE/CNA references
CWE sourceCNA
NVD statusNVD enriched

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Affected versionsThe structured affected or fixed version information changed.
    Before
    n/a · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
    After
    Cisco Adaptive Security Appliance (ASA) Software: n/a · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Added to CISA KEV
Fixed release or patch reference recorded
ENISA EUVD · EUVD-2020-24851↗CISA KEV record↗CVE authority or vendor reference · Cisco CISCO-SA-ASAFTD-XSS-MULTIPLE-FCB3VPZE↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2020-3580 · cve.blacktree.nl