How severe is CVE-2020-3564?

CVE-2020-3564 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.

Is CVE-2020-3564 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (67th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-3564?

CVE-2020-3564 primarily affects Cisco Adaptive Security Appliance. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2020-3564?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2020-3564 published?

CVE-2020-3564 was published on 2020-10-21 and last updated on 2026-06-17.

CVE-2020-3564

CVE-2020-3564 is a medium-severity vulnerability in Cisco Adaptive Security Appliance with a CVSS 3.x base score of 5.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-436.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
CVSS v2: 5.0
EPSS exploit prediction: 1% (67th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-436
Affected product: Cisco Adaptive Security Appliance
Published: 2020-10-21
Last modified: 2026-06-17

Description

A vulnerability in the FTP inspection engine of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass FTP inspection. The vulnerability is due to ineffective flow tracking of FTP traffic. An attacker could exploit this vulnerability by sending crafted FTP traffic through an affected device. A successful exploit could allow the attacker to bypass FTP inspection and successfully complete FTP connections.

Frequently asked questions

What is CVE-2020-3564?: A vulnerability in the FTP inspection engine of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass FTP inspection. The vulnerability is due to ineffective flow tracking of FTP traffic. An attacker could exploit this vulnerability by sending crafted FTP traffic through an affected device. A successful exploit could allow the attacker to bypass FTP inspection and successfully complete FTP connections.
How severe is CVE-2020-3564?: CVE-2020-3564 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.
Is CVE-2020-3564 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (67th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-3564?: CVE-2020-3564 primarily affects Cisco Adaptive Security Appliance. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2020-3564?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2020-3564 published?: CVE-2020-3564 was published on 2020-10-21 and last updated on 2026-06-17.

References

https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-ftpbypass-HY3UTxYu

Affected products (3)

cpe:2.3:a:cisco:adaptive_security_appliance:*:*:*:*:*:*:*:*
cpe:2.3:a:cisco:firepower_threat_defense:*:*:*:*:*:*:*:*
cpe:2.3:o:cisco:adaptive_security_appliance_software:*:*:*:*:*:*:*:*

More vulnerabilities in Cisco Adaptive Security Appliance

CVE-2021-1573 — High (CVSS 8.6): A vulnerability in the web services interface of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower…
CVE-2021-40118 — High (CVSS 8.6): A vulnerability in the web services interface of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower…
CVE-2021-40117 — High (CVSS 8.6): A vulnerability in SSL/TLS message handler for Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower…
CVE-2021-34793 — High (CVSS 8.6): A vulnerability in the TCP Normalizer of Cisco Adaptive Security Appliance (ASA) Software and Firepower Threat Defense…
CVE-2020-3572 — High (CVSS 8.6): A vulnerability in the SSL/TLS session handler of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower…
CVE-2020-3529 — High (CVSS 8.6): A vulnerability in the SSL VPN negotiation process for Cisco Adaptive Security Appliance (ASA) Software and Cisco…

All CVEs affecting Cisco Adaptive Security Appliance →

Other CWE-436 vulnerabilities

CVE-2023-24813 — Critical (CVSS 10.0): Dompdf is an HTML to PDF converter written in php. Due to the difference in the attribute parser of Dompdf and…
CVE-2026-8034 — Critical (CVSS 9.8): A server-side request forgery (SSRF) vulnerability was identified in the GitHub Enterprise Server notebook viewer that…
CVE-2021-45327 — Critical (CVSS 9.8): Gitea before 1.11.2 is affected by Trusting HTTP Permission Methods on the Server Side when referencing the vulnerable…
CVE-2020-10180 — Critical (CVSS 9.8): The ESET AV parsing engine allows virus-detection bypass via a crafted BZ2 Checksum field in an archive. This affects…
CVE-2019-19589 — Critical (CVSS 9.8): The Lever PDF Embedder plugin 4.4 for WordPress does not block the distribution of polyglot PDF documents that are…
CVE-2026-14198 — Critical (CVSS 9.1): @fastify/middie versions 9.1.0 through 9.3.2 decode the encoded slash %2F inside path parameter values before matching…

Browse all CWE-436 vulnerabilities →