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Fencer Vulns
medium 5.8

CVE-2020-3564 json

Cisco Adaptive Security Appliance Software and Firepower Threat Defense Software FTP Inspection Bypass Vulnerability

published 2020-10-21 6 y ago modified 2026-08-11 2 mo ago also EUVD-2020-24835

cvss
5.8
version 3.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.3%
EPSS 1.3% chance of exploitation in 30 days, percentile 71%
public exploits
0
none known

Summary

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.

Patch / fix

  • cisco adaptive_security_appliance 9.6
  • cisco secure_firewall_threat_defense 6.3.0.6, 6.4.0.10, 6.5.0.5, 6.6.1
  • cisco adaptive_security_appliance_software 9.8.4.26, 9.9.2.80, 9.10.1.44, 9.12.4.4, 9.13.1.13, 9.14.1.19

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
23 mo ago

Exploit prediction

1.34% chance of exploitation in the next 30 days, higher than 71% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.0 5.8 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
NVD 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:P/A:N

Affected products

  • Cisco Cisco Adaptive Security Appliance (ASA) Software

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.