CVE-2026-20079

Cisco Secure Firewall Management Center Authentication Bypass Remote Code Execution Vulnerability

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. 

Affected

Cisco · Cisco Secure Firewall Management Center (FMC)

CVSS v3.1 CISCO

10.0 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

EPSS

88.18% chance of exploitation in the next 30 days, 100th percentile

CISA KEV

added 2026-09-09

Nuclei

critical · CWE-288

Published

2026-03-04

Updated

2026-09-16

Proof-of-concept exploits (3)

• https://blog.talosintelligence.com/fmc-ongoing-exploitation/
• 0xBlackash/CVE-2026-200790★ · 2026-03-28
• CyberAuth/CVE-2026-200796★ · 2026-08-24

Nuclei templates (1)

• projectdiscovery/nuclei-templates/blob/main/http/cves/2026/CVE-2026-20079.yaml

Metasploit modules (1)

• rapid7/metasploit-framework/blob/master/modules/exploits/linux/http/cisco_fmc_auth_bypass…

Security advisories

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-on…
• http://seclists.org/fulldisclosure/2026/Aug/80
• https://blog.talosintelligence.com/fmc-ongoing-exploitation

References

• CVE Record
• NVD entry