Cisco Firewall Management Center's Authentication Bypass via an Alternate Path Grants Unauthenticated Remote Attackers Full Administrative Control; CISA's September 12th KEV Deadline Has Passed

Last refreshed2026-09-27

Status: KEV | Advisory ID: CVE-2026-20079

Key Details

CVE	CVE-2026-20079
Vulnerability Name	Cisco Firewall Management Center Authentication Bypass Using an Alternate Path or Channel Vulnerability
CVSS Score / Version	10.0 (Critical) / CVSS v3.1
Updated	2026-09-22
CVSS Vector	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H`
CVSS Prose	attack vector is network; attack complexity is low; privileges required is none; user interaction is none; scope is changed; confidentiality impact is high; integrity impact is high; availability impact is high.
Affected products	Cisco Secure Firewall Management Center (FMC) and Security Cloud Control (SCC) Firewall Management and Cisco Secure Firewall Management Center
Exploitation status	In August 2026, the Cisco PSIRT became aware of active exploitation of this vulnerability.
Classified as	CWE-288 (Authentication Bypass Using an Alternate Path or Channel)
KEV listing	Added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2026-09-09.
Exploitation prediction (EPSS)	88.18% probability of exploitation in the next 30 days (100% percentile) -- FIRST.org's EPSS model.
Federal remediation deadline	2026-09-12 (CISA KEV, Binding Operational Directive).

Affected Products, Subsystems & Sectors

Vendor	Product	Affected Versions	Patch Status
Cisco	Secure Firewall Management Center (FMC) and Security Cloud Control (SCC) Firewall Management
Cisco	Secure Firewall Management Center

Vendor

Product

Affected Versions

Patch Status

Cisco

Secure Firewall Management Center (FMC) and Security Cloud Control (SCC) Firewall Management

Cisco

Secure Firewall Management Center

Subsystems	Core Infrastructure, Industrial Network - Routers/Firewalls
Sectors	Critical Manufacturing, Energy, Transportation Systems, Water and Wastewater Systems

What to Know

A vulnerability in the web interface of Cisco Secure Firewall Management Center (FMC) Software could allow an unauthenticated, remote attacker to bypass authentication and execute script files on an affected device to obtain root access to the underlying operating system.

This vulnerability is due to an improper system process that is created at boot time. An attacker could exploit this vulnerability by sending crafted HTTP requests to an affected device. A successful exploit could allow the attacker to execute a variety of scripts and commands that allow root access to the device.

What to Do

Workarounds: No workarounds available. Cisco strongly recommends that customers upgrade to the fixed software indicated in this advisory.

References

Source	Reference
NVD	https://nvd.nist.gov/vuln/detail/CVE-2026-20079
CVE	https://www.cve.org/CVERecord?id=CVE-2026-20079
Vendor advisory	https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-onprem-fmc-authbypass-5JPp45V2

Source

Reference

NVD

https://nvd.nist.gov/vuln/detail/CVE-2026-20079

CVE

https://www.cve.org/CVERecord?id=CVE-2026-20079

Vendor advisory

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-onprem-fmc-authbypass-5JPp45V2

KEV Required Action

Field	Value
KEV Link	https://www.cisa.gov/known-exploited-vulnerabilities-catalog
Date Added to KEV	2026-09-09
Required Action Due Date	2026-09-12
Required Action	Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

Field

Value

KEV Link

https://www.cisa.gov/known-exploited-vulnerabilities-catalog

Date Added to KEV

2026-09-09

Required Action Due Date

2026-09-12

Required Action

Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.