Deserialization in Cisco Secure Firewall Management Center (Fmc)

CVE-2026-20131

A vulnerability in the web-based management interface of Cisco Secure Firewall Management Center (FMC) Software could allow an unauthenticated, remote attacker to execute arbitrary Java code as root on an affected device. This vuln…

Vulnerability class: Insecure Deserialization

EPSS: 0.014 (80.8th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 10.0 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H.

Affected products

Weakness classification (CWE)

CISA KEV (Known Exploited Vulnerabilities)

This CVE is on the CISA KEV catalog, added on . CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.

BOD 22-01 due date: .

Required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Known ransomware campaign use: yes.

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2026-20131?
CVE-2026-20131 is a critical-severity vulnerability in Cisco Secure Firewall Management Center (Fmc), classified under Deserialization of Untrusted Data. CVSS score: 10.0/10. Published 2026-03-04.
How severe is CVE-2026-20131?
Critical severity. CVSS v3 base score is 10.0 out of 10.
Is CVE-2026-20131 known to be exploited?
Yes. CVE-2026-20131 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2026-03-19), indicating it is being actively exploited. 4 public proof-of-concept repositories are indexed.