Cisco Secure Firewall Management Center (FMC) Software and Cisco Security Cloud Control (SCC) Firewall Management Deserialization of Untrusted Data Vulnerability

Critical Threat Advisory: This vulnerability is documented in active Ransomware campaigns. Immediate remediation required.

Technical Severity

CVSS v3.1 Metrics

CRITICAL

10 / 10

Minimal Risk Critical

Vector Specification

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Exploitation Likelihood

EPSS Prediction

0.60 %

Predictive Probability

Percentile Rank

69.2 th

Documented as more likely to be exploited than 69.2% of known CVEs.

Detection Date

Mar 19, 2026

Remediation Due

Mar 22, 2026

CISA Catalog Active

Threat Analysis

Cisco Secure Firewall Management Center (FMC) Software and Cisco Security Cloud Control (SCC) Firewall Management contain a deserialization of untrusted data vulnerability in the web-based management interface that could allow an unauthenticated, remote attacker to execute arbitrary Java code as root on an affected device.

Remediation Directive

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

External Intelligence

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmc-rce-NKhnULJh

NVD

National Vulnerability Database

https://nvd.nist.gov/vuln/detail/CVE-2026-20131