CVE intelligence

CVE-2026-20343

Vulnerability intelligence

Published Sep 16, 2026Sources checked Nov 10, 2026

7.5HIGHCVSS out of 10

What this means

Review the available evidence

CVE-2026-20343 and is rated High severity with a CVSS score of 7.5. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

What to do next

Remediation and response

Cisco Security Advisories guidance

Vendor revision: Sep 16, 2026

To remediate these vulnerabilities, Cisco strongly recommends that customers upgrade to the fixed software that is indicated in the advisories.

Cisco Security Advisories guidance

Vendor revision: Sep 16, 2026

Cisco has released software updates that address these vulnerabilities.

CISA KEVNot listedBased on the latest collected catalog

EPSS0.7%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2026-20343?

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.

Source: NVD