What is CVE-2020-3577?

CVE-2020-3577 is a high-severity vulnerability in Cisco Firepower Threat Defense Software, classified under Improper Input Validation. CVSS score: 7.4/10. Published 2020-10-21.

How severe is CVE-2020-3577?

High severity. CVSS v3 base score is 7.4 out of 10.

Improper input validation in Cisco Firepower Threat Defense Software

CVE-2020-3577

A vulnerability in the ingress packet processing path of Cisco Firepower Threat Defense (FTD) Software for interfaces that are configured either as Inline Pair or in Passive mode could allow an unauthenticated, adjacent attacker to cause a denial of service (DoS) condition. The vulnerability is due to insufficient validation when Ethernet frames are processed. An attacker could exploit this vulnerability by sending malicious Ethernet frames through an affected device. A successful exploit could allow the attacker do either of the following: Fill the /ngfw partition on the device: A full /ngfw partition could result in administrators being unable to log in to the device (including logging in through the console port) or the device being unable to boot up correctly. Note: Manual intervention is required to recover from this situation. Customers are advised to contact the Cisco Technical Assistance Center (TAC) to help recover a device in this condition. Cause a process crash: The process crash would cause the device to reload. No manual intervention is necessary to recover the device after the reload.

Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)

Published 2020-10-21 · last modified 2026-08-11.

CVSS v3 metric

CVSS v3 base score 7.4 (High). Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.004 (35.4th percentile), scored 2026-10-05.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 35th percentile — 35.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000

Affected products

Weakness classification (CWE)

CWE-20 — Improper Input Validation

References

tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-inli… (vendor-advisory, Vendor Advisory)

Frequently asked questions

What is CVE-2020-3577?: CVE-2020-3577 is a high-severity vulnerability in Cisco Firepower Threat Defense Software, classified under Improper Input Validation. CVSS score: 7.4/10. Published 2020-10-21.
How severe is CVE-2020-3577?: High severity. CVSS v3 base score is 7.4 out of 10.