Cyber Posture

CVE-2026-20079

Critical

Published: 04 March 2026

Published
04 March 2026
Modified
05 March 2026
KEV Added
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Patch
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CVSS Score 10.0 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
EPSS Score 0.1183 93.8th percentile
Risk Priority 27 60% EPSS · 20% KEV · 20% CVSS

Description

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.…

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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.

Mitigating Controls (NIST 800-53 r5)AI

SI-2 Flaw Remediation good match
prevent

Directly mitigates the CVE by requiring timely remediation of the authentication bypass flaw through patching affected FMC software versions.

AC-3 Access Enforcement good match
prevent

Enforces approved authorizations for access to the web interface, preventing unauthenticated attackers from bypassing authentication to execute scripts and gain root access.

SI-10 Information Input Validation good match
prevent

Validates crafted HTTP inputs to the web interface, blocking the exploitation vector that triggers the improper boot-time process leading to root access.

Security SummaryAI

CVE-2026-20079 is a critical authentication bypass vulnerability (CVSS 10.0) in the web interface of Cisco Secure Firewall Management Center (FMC) Software. The issue stems from an improper system process created at boot time, which allows an unauthenticated, remote attacker to bypass authentication mechanisms and execute arbitrary script files on an affected device, ultimately granting root access to the underlying operating system. This flaw is classified under CWE-288.

An unauthenticated, remote attacker can exploit this vulnerability by sending crafted HTTP requests to the web interface of a vulnerable FMC device. Successful exploitation enables the attacker to execute a variety of scripts and commands, providing full root-level control over the device, including potential data exfiltration, modification of configurations, or further lateral movement within the network.

For mitigation details, including affected versions and patch information, refer to the Cisco Security Advisory at https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-onprem-fmc-authbypass-5JPp45V2.

Details

CWE(s)
CWE-288

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
Why these techniques?

The vulnerability enables unauthenticated remote attackers to exploit the public-facing web interface (T1190) for arbitrary script execution and root access, directly facilitating exploitation for privilege escalation (T1068).

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

References