---
id: CVE-2026-20343
title: "A vulnerability in a critical API for Cisco Secure FMC Software could allow an unauthenticated, remote attacker to download sensitive files and use unbounded disk space.\r\n\r\nThis vulnerability exists because a critical API lacks authentic…"
summary: "A vulnerability in a critical API for Cisco Secure FMC Software could allow an unauthenticated, remote attacker to download sensitive files and use unbounded disk space.\r\n\r\nThis vulnerability exists because a critical API lacks authentic…"
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-306
vendor: Cisco
product: Cisco Secure Firewall Management Center (FMC)
affected:
  - secure_firewall_management_center_fmc 7.3.0
  - secure_firewall_management_center_fmc 7.3.1
  - secure_firewall_management_center_fmc 7.3.1.1
  - secure_firewall_management_center_fmc 7.4.0
  - secure_firewall_management_center_fmc 7.4.1
  - secure_firewall_management_center_fmc 7.4.1.1
  - secure_firewall_management_center_fmc 7.3.1.2
  - secure_firewall_management_center_fmc 7.6.0
  - secure_firewall_management_center_fmc 7.4.2
  - secure_firewall_management_center_fmc 7.4.2.1
  - secure_firewall_management_center_fmc 7.7.0
  - secure_firewall_management_center_fmc 7.4.2.2
  - secure_firewall_management_center_fmc 7.6.1
  - secure_firewall_management_center_fmc 7.4.2.3
  - secure_firewall_management_center_fmc 7.6.2
  - secure_firewall_management_center_fmc 7.7.10
  - secure_firewall_management_center_fmc 7.6.2.1
  - secure_firewall_management_center_fmc 7.7.10.1
  - secure_firewall_management_center_fmc 7.4.2.4
  - secure_firewall_management_center_fmc 7.4.3
  - secure_firewall_management_center_fmc 7.6.3
  - secure_firewall_management_center_fmc 7.7.11
  - secure_firewall_management_center_fmc 7.6.4
  - secure_firewall_management_center_fmc 10.0.0
  - secure_firewall_management_center_fmc 7.4.4
  - secure_firewall_management_center_fmc 7.4.5
  - secure_firewall_management_center_fmc 7.7.12
  - secure_firewall_management_center_fmc 7.6.5
  - secure_firewall_management_center_fmc 7.4.6
  - secure_firewall_management_center_fmc 10.0.1
  - secure_firewall_management_center_fmc 7.4.7
published: '2026-09-16'
updated: '2026-09-18'
sourceUpdated: '2026-09-18T15:17:07.577'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-20343'
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
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-09-18T14:39:35.675985Z'
epss: 0.0045
epssPercentile: 0.36488
ingestedAt: '2026-09-16T16:37:52.202Z'
---

## Overview

A vulnerability in a critical API for Cisco Secure FMC Software could allow an unauthenticated, remote attacker to download sensitive files and use unbounded disk space.

This vulnerability exists because a critical API lacks authentication. An attacker could exploit this vulnerability by repeatedly invoking the API. A successful exploit could allow the attacker to download sensitive files that should be restricted and consume disk space so the device could become unresponsive, causing a DoS condition.

## 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)