CVE-2020-3580: Cisco ASA and FTD Cross-Site Scripting (XSS) Vulnerability
- Is it exploited?
Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 3 Nov 2021, 378 days after the CVE record was published.
- How likely is exploitation in the next 30 days?
- 85.6%
EPSS score, percentile 99.7 of all scored records
- How severe?
- 6.1 Medium
CVSS v3.1 base score, given by the CNA
- What should I do?
Required action (CISA), due 3 May 2022: Apply updates per vendor instructions.
- Which versions are affected?
Affected: unspecified
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
What to do
Required action, set by CISA
Apply updates per vendor instructions.
CISA due date for this action: 3 May 2022.
Advisories and patches
Linked from CISA's catalog entry
Affected products and versions
As listed in the CVE record.
| Status | Versions |
|---|---|
| Affected | unspecified |
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
About this vulnerability
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.
Summary: CISA's KEV catalog, as of 28 Oct 2026.
- CISA added CVE-2020-3580 to its Known Exploited Vulnerabilities (KEV) catalog on 3 Nov 2021.
- CISA marks it as known to be used in ransomware campaigns.
- The due date CISA sets for the required action is 3 May 2022.
- The CVE record was published on 21 Oct 2020, 378 days before it was added to KEV.
- The CVE record carries a CVSS v3.1 base score of 6.1 (Medium), given by its CNA.
- FIRST's EPSS model puts the probability of exploitation in the next 30 days at 85.6% (percentile 99.7), as of 28 Oct 2026.
- CISA's SSVC assessment in the CVE record: exploitation active, automatable no, technical impact partial.
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026. About the data.
Description
Cisco Adaptive Security Appliance Software and Firepower Threat Defense Software Web Services Interface Cross-Site Scripting Vulnerabilities
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.
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
Weakness
CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.
Timeline
| Date | Event |
|---|---|
| 21 Oct 2020 | CVE record published |
| 3 Nov 2021 | Added to CISA KEV |
| 3 May 2022 | CISA due date for the required action |
| 21 Oct 2025 | CVE record last updated |
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