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Known exploited vulnerability

CVE-2026-20079

criticalCVSS 3.1 10.0In CISA KEVEPSS 89%Published · Cisco

The short answer

CVE-2026-20079 affects Cisco Cisco Secure Firewall Management Center (FMC) and is rated critical (CVSS 10.0). CISA added it to the Known Exploited Vulnerabilities catalog on 2026-09-09: attackers are using it, so patch it first.

What it is

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. 

Weakness: CWE-288.

Severity

10.0 critical

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

Exploited (CISA KEV)

Yes, since Sep 9, 2026

Federal due date Sep 12, 2026

EPSS, next 30 days

89%

Higher than 100% of scored CVEs

How it can be exploited

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Changed
Confidentiality impact
High
Integrity impact
High
Availability impact
High

What CISA says to do

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…

Affected products

Cisco Secure Firewall Management Center (FMC). NVD's record lists the exact affected versions.

References

Questions

Is CVE-2026-20079 being exploited?

Yes. CISA added CVE-2026-20079 to its Known Exploited Vulnerabilities catalog on 2026-09-09, with a federal remediation due date of 2026-09-12.

How do I fix CVE-2026-20079?

CISA's 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…

From NVD, CISA KEV, FIRST EPSS and OSV.dev, checked . Status on NVD: Analyzed. The description is NVD's text, quoted as published.

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