CVE-2020-3580
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.
- CVSS
- 6.1Mediumscored by the publisher (CNA)
- Exploited in the wild
- Yes, in CISA KEV since 3 Nov 2021CISA deadline for US federal agencies: 3 May 2022known use in ransomware campaignsunvetted proof-of-concept code on github
- EPSS
- 85.6%chance of exploitation in the next 30 daystop 0.3% of scored CVEsFIRST score of 11 Nov 2026
- Fix
- Patch availablesee the advisories in the references
- Published
- 21 Oct 2020analysed here 12 Nov 2026
Do first. Apply updates per vendor instructions. (CISA's required action for this KEV entry)
Summary
Triage
The summary, impact and action text on this page are written by our AI analysis pipeline, or taken from the NVD description when a CVE was imported from NVD. They are not the vendor's wording: check them against the sources. A longer AI executive summary and technical analysis are generated for signed-in accounts on the Max plan.
Affected products
Products named in our analysis
- cisco:secure_firewall_threat_defense
- cisco:adaptive_security_appliance_software
Fix and mitigation
WAF and other mitigations
Can a WAF block it? Yes. Cross-site scripting sends script tags or event handlers in the request, which WAF signatures match well.
Also consider: CSP · output encoding
Based on the weakness type only; no CVE-specific evidence yet. We check Cloudflare, AWS, Google Cloud Armor and Azure; for Akamai, Imperva, Fastly, F5, ask your vendor.
Remediation steps (AI-written)
Step-by-step remediation is generated for accounts on the Max plan, for CVEs that match a technology in their stack. Add this technology to your stack to see the fix checklist.
Exploitation evidence
- CISA KEV catalog
- Listed since 3 Nov 2021. Known use in ransomware campaigns.
- CISA due date
- 3 May 2022, the remediation deadline for US federal agencies
- CISA required action
- Apply updates per vendor instructions.
- Public exploit code
- Unvetted proof-of-concept code on GitHub: 4 GitHub proofs of concept · 1 Nuclei template
- CISA SSVC
- exploitation active, automatable no, technical impact partialAssessed by CISA 8 Nov 2024 (SSVC 2.0.3). Exploitation is none, poc (public proof of concept) or active.
Nuclei
- Cisco ASA/FTD Software - Cross-Site Scriptingdetection template, medium
GitHub proofs of concept
- adarshvs/CVE-2020-358019 stars
- Hudi233/CVE-2020-35809 stars
- catatonicprime/CVE-2020-35802 stars
- cruxN3T/CVE-2020-35800 stars
Listed so you can judge urgency, not as a recommendation to run anything. GitHub “proofs of concept” are unvetted: some are fake or carry malware. Exploit-DB marks the entries its staff verified.
Timeline
- 21 Oct 2020Published
- 25 Jun 2021First proof-of-concept repository on GitHub (unvetted)246 days (about 8 months) later
- 3 Nov 2021Added to CISA KEV (exploited in the wild)131 days (about 4 months) later
- 3 May 2022CISA remediation due date (US federal agencies)181 days (about 6 months) later
- 8 Nov 2024CISA SSVC assessment: exploitation active921 days (about 3 years) later
- 21 Oct 2025CVE record last updated347 days (about 12 months) later
- 12 Nov 2026Analysed by vulneraibility.com387 days (about 1 year) later
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
| Metric | Value | What it means |
|---|---|---|
| Attack vector | NetworkReachable over the internet or any routable network. | Reachable over the internet or any routable network. |
| Attack complexity | LowRepeatable attack, no special conditions. | Repeatable attack, no special conditions. |
| Privileges required | NoneThe attacker needs no prior access. | The attacker needs no prior access. |
| User interaction | RequiredA victim must click, open or otherwise cooperate. | A victim must click, open or otherwise cooperate. |
| Scope | ChangedImpact crosses a security boundary into other components. | Impact crosses a security boundary into other components. |
| Confidentiality | LowPartial data disclosure. | Partial data disclosure. |
| Integrity | LowLimited modification possible. | Limited modification possible. |
| Availability | NoneThe service stays up. | The service stays up. |
Common questions
Is CVE-2020-3580 being exploited?
Yes. CVE-2020-3580 appears in CISA's Known Exploited Vulnerabilities catalog, which means exploitation in the wild has been confirmed and reported. Treat it as active rather than theoretical, and patch it ahead of higher-scoring vulnerabilities that carry no exploitation evidence.
How severe is CVE-2020-3580?
CVE-2020-3580 is rated Medium with a CVSS score of 6.1. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2020-3580?
Yes. A fix has been recorded for CVE-2020-3580. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2020-3580 affect?
CVE-2020-3580 affects cisco:secure_firewall_threat_defense, cisco:adaptive_security_appliance_software. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
References
2 references in the CVE record, grouped by the tags the record gives them.
Advisories (1)
- tools.cisco.com /security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-xss-multiple-FCB3
Other links (1)
- cisa.gov /known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-3580
Where the data on this page comes from
- CVE List (CVE.org): description, affected versions, references; CVE Terms of Use
- NVD: CVSS and CPE data
- CISA KEV catalog: exploitation, date added, due date
- CISA Vulnrichment (ADP): SSVC decision points
- FIRST EPSS: exploit probability and percentile
- Nuclei templates: detection templates
- PoC-in-GitHub: GitHub repositories that claim a proof of concept
Summary, impact and triage tags: written by our AI analysis pipeline from the sources above. Check them against the sources.
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