High severity · published Sep 16, 2026
CVE-2026-20343
Cisco Secure Firewall Management Center Software Information Disclosure and Disk Denial of Service Vulnerability
7.5
CVSS
0.7%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.7% · higher than 51% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
CS
Cisco Secure Firewall Management Center (FMC) · Cisco
7.3.0; 7.3.1; 7.3.1.1; 7.4.0; 7.4.1; 7.4.1.1; +25 more · source: vendor
Affected product
CS
Cisco Secure Firewall Management Center (FMC)
Cisco
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-20343
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-20343
sec.cloudapps.cisco.com
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmc-mulivulns-4PsnFwvx
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