Critical [CVE-2026-20079] Cisco Secure Firewall Management Center Software Authentication Bypass Vulnerability
This critical-severity Cisco advisory covers CVE-2026-20079 affecting Cisco Secure Firewall Management Center (FMC).
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Summary
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.
Note: If the FMC management interface does not have public internet access, the attack surface that is associated with this vulnerability is reduced.
Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.
This advisory is part of the March 2026 release of the Cisco Secure Firewall ASA, Secure FMC, and Secure FTD Software Security Advisory Bundled Publication.
CISA Known Exploited Vulnerability
- Listed:
- Sep 9, 2026 · federal remediation due Sep 12, 2026
- 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.
- Ransomware use:
- Unknown
KEV is a prioritization signal from CISA — remediation detail still comes from the vendor advisory.
- Scope: This vulnerability affects Cisco Secure FMC Software, regardless of device configuration.
Official advisory · high-confidence parse· fetched 3 months ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 3 months ago·verify at source
Mitigation checklist
- There are no workarounds that address this vulnerability.
Official advisory · high-confidence parse· fetched 3 months ago·verify at source
Discussion(0)
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