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No exploitation reportedFix available

CVE-2020-3554

No exploitation reported by the sources we read.

  • Published2020-10-21
  • Fixed in6.5.0.5 · 6.4.0.10
  • WeaknessCWE-400

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

A vulnerability in the TCP packet processing of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to a memory exhaustion condition. An attacker could exploit this vulnerability by sending a high rate of crafted TCP traffic through an affected device. A successful exploit could allow the attacker to exhaust device resources, resulting in a DoS condition for traffic transiting the affected device.

Timeline

dates in UTC
  1. 2020-10-2119:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2020-3554?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2020-3554?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD
Cisco secure firewall threat defense
BranchAffectedFixed in
6.5≥ 6.5.0, < 6.5.0.56.5.0.5
6.x≥ 6.3.0, < 6.4.0.106.4.0.10
6.2≤ 6.2.2no fix published
6.6= 6.6.0no fix published
Cisco ASA
BranchAffectedFixed in
9.14≥ 9.14.0, < 9.14.1.309.14.1.30
9.13≥ 9.13.0, < 9.13.1.139.13.1.13
Cisco adaptive security appliance
BranchAffectedFixed in
9.12< 9.12.4.39.12.4.3

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

  1. Update Cisco secure firewall threat defense to 6.5.0.5 · 6.4.0.10

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub

Sources

  • CISA-ADPSSVC decisionnone2024-11-13
  • OpenCVESSVC decisionnone—
  • NVDCVSS 3.17.5read 2026-10-23
  • CNACVSS 3.08.6read 2026-10-23
  • NVDCVSS 2.07.8read 2026-10-23
  • CNAweakness (CWE)CWE-400read 2026-10-23
  • NVDweakness (CWE)CWE-400read 2026-10-23
  • FIRST EPSSEPSS score2.7 %2026-10-23

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published
2020-10-21
Last Modified
2026-08-11
NVD status
Modified

Frequently asked questions

What is CVE-2020-3554?

A vulnerability in the TCP packet processing of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to a memory exhaustion condition. An attacker could exploit this vulnerability by sending a high rate of crafted TCP traffic through an affected device. A successful exploit could allow the attacker to exhaust device resources, resulting in a DoS condition for traffic transiting the affected device.

Is CVE-2020-3554 actively exploited?

Active exploitation of CVE-2020-3554 has not been confirmed. Its EPSS score was 2.7% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2020-3554?

CVE-2020-3554 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

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