---
id: CVE-2026-20340
title: "A vulnerability in Cisco Secure FMC Software could allow an authenticated, remote attacker to execute arbitrary commands at the root privilege level.\r\n\r\nThis vulnerability is due to unsecured deserialization of web-management user-c…"
summary: "A vulnerability in Cisco Secure FMC Software could allow an authenticated, remote attacker to execute arbitrary commands at the root privilege level.\r\n\r\nThis vulnerability is due to unsecured deserialization of web-management user-c…"
severity: high
cvss: 8.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-502
vendor: Cisco
product: Cisco Secure Firewall Management Center (FMC)
affected:
  - secure_firewall_management_center_fmc 7.0.0
  - secure_firewall_management_center_fmc 7.0.0.1
  - secure_firewall_management_center_fmc 7.0.1
  - secure_firewall_management_center_fmc 7.0.1.1
  - secure_firewall_management_center_fmc 7.0.2
  - secure_firewall_management_center_fmc 7.2.0
  - secure_firewall_management_center_fmc 7.0.2.1
  - secure_firewall_management_center_fmc 7.0.3
  - secure_firewall_management_center_fmc 7.2.0.1
  - secure_firewall_management_center_fmc 7.0.4
  - secure_firewall_management_center_fmc 7.2.1
  - secure_firewall_management_center_fmc 7.0.5
  - secure_firewall_management_center_fmc 7.3.0
  - secure_firewall_management_center_fmc 7.2.2
  - secure_firewall_management_center_fmc 7.3.1
  - secure_firewall_management_center_fmc 7.2.3
  - secure_firewall_management_center_fmc 7.2.3.1
  - secure_firewall_management_center_fmc 7.2.4
  - secure_firewall_management_center_fmc 7.0.6
  - secure_firewall_management_center_fmc 7.2.4.1
  - secure_firewall_management_center_fmc 7.2.5
  - secure_firewall_management_center_fmc 7.3.1.1
  - secure_firewall_management_center_fmc 7.4.0
  - secure_firewall_management_center_fmc 7.0.6.1
  - secure_firewall_management_center_fmc 7.2.5.1
  - secure_firewall_management_center_fmc 7.4.1
  - secure_firewall_management_center_fmc 7.2.6
  - secure_firewall_management_center_fmc 7.4.1.1
  - secure_firewall_management_center_fmc 7.0.6.2
  - secure_firewall_management_center_fmc 7.2.7
  - secure_firewall_management_center_fmc 7.2.5.2
  - secure_firewall_management_center_fmc 7.3.1.2
  - secure_firewall_management_center_fmc 7.2.8
  - secure_firewall_management_center_fmc 7.6.0
  - secure_firewall_management_center_fmc 7.4.2
  - secure_firewall_management_center_fmc 7.2.8.1
  - secure_firewall_management_center_fmc 7.0.6.3
  - secure_firewall_management_center_fmc 7.4.2.1
  - secure_firewall_management_center_fmc 7.2.9
  - secure_firewall_management_center_fmc 7.0.7
  - secure_firewall_management_center_fmc 7.7.0
  - secure_firewall_management_center_fmc 7.4.2.2
  - secure_firewall_management_center_fmc 7.2.10
  - secure_firewall_management_center_fmc 7.6.1
  - secure_firewall_management_center_fmc 7.4.2.3
  - secure_firewall_management_center_fmc 7.0.8
  - secure_firewall_management_center_fmc 7.6.2
  - secure_firewall_management_center_fmc 7.7.10
  - secure_firewall_management_center_fmc 7.2.10.1
  - secure_firewall_management_center_fmc 7.0.8.1
published: '2026-09-16'
updated: '2026-09-18'
sourceUpdated: '2026-09-18T13:28:28.567'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-20340'
references:
  - url: >-
      https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmc-mulivulns-4PsnFwvx
    label: psirt@cisco.com
  - url: 'https://software.cisco.com'
tags:
  - nvd
  - cve.org
  - csaf
  - vendor-advisory
  - cisco
epss: 0.00694
epssPercentile: 0.50838
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-09-17T16:02:18.636037Z'
ingestedAt: '2026-09-16T16:37:52.201Z'
---

## Overview

A vulnerability in Cisco Secure FMC Software could allow an authenticated, remote attacker to execute arbitrary commands at the root privilege level.

This vulnerability is due to unsecured deserialization of web-management user-controlled data. An attacker could exploit this vulnerability by authenticating to the device and sending a crafted HTTP payload. A successful exploit could allow the attacker to save the crafted payload and then execute it on the underlying operating system as root.
To exploit this vulnerability, the attacker must have valid credentials for a user account with at least the role of Security Analyst (read-only).

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **cisco-sa-fmc-mulivulns-4PsnFwvx** · Cisco · affected: Cisco Secure Firewall Management Center (FMC) Appliances · updated 2026-09-16 · [advisory](https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmc-mulivulns-4PsnFwvx)