CVE-2026-20131: Cisco Secure Firewall Management Center (FMC) Software and Cisco Security Cloud Control (SCC) Firewall Management Deserialization of Untrusted Data Vulnerability

CISA Known Exploited Vulnerabilities

Name

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

Vendor

Cisco

Product

Secure Firewall Management Center (FMC)

Added to the catalog

2026-03-19

Due date for US federal agencies

2026-03-22

Weaknesses

CWE-502

Catalog version

2026.10.30

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.

Required action (CISA)

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

Ransomware use: CISA marks this vulnerability as known to be used in ransomware campaigns. CISA does not say which group used it.

Links in CISA's notes

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmc-rce-NKhnULJh
• https://nvd.nist.gov/vuln/detail/CVE-2026-20131

Read on 2026-11-02T23:39:54.475Z under licence cisa-kev-cc0@b0067899 from https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json

NVD analysis

Status

Analyzed

Published

2026-03-04T18:16:27.153

Last modified

2026-06-17T10:17:10.937

Weaknesses

CWE-502

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 vulnerability is due to insecure deserialization of a user-supplied Java byte stream. An attacker could exploit this vulnerability by sending a crafted serialized Java object to the web-based management interface of an affected device. A successful exploit could allow the attacker to execute arbitrary code on the device and elevate privileges to root.
Note: If the FMC management interface does not have public internet access, the attack surface that is associated with this vulnerability is reduced.

References

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmc-rce-NKhnULJh (Vendor Advisory)
• https://aws.amazon.com/blogs/security/amazon-threat-intelligence-teams-identify-interlock-ransomware-campaign-targeting-enterprise-firewalls/ (Technical Description)
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-20131 (US Government Resource)

This product uses the NVD API but is not endorsed or certified by the NVD.

Read on 2026-11-02T23:42:22.836Z under licence nvd-api-terms-of-use@ff2a5288 from https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-20131

CVE record

Title (CNA)

Cisco Secure Firewall Management Center Software Remote Code Execution Vulnerability

Assigner

cisco

State

PUBLISHED

Published

2026-03-04T17:17:56.008Z

Updated

2026-08-14T03:55:24.856Z

Problem types

Deserialization of Untrusted Data

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 vulnerability is due to insecure deserialization of a user-supplied Java byte stream. An attacker could exploit this vulnerability by sending a crafted serialized Java object to the web-based management interface of an affected device. A successful exploit could allow the attacker to execute arbitrary code on the device and elevate privileges to root.
Note: If the FMC management interface does not have public internet access, the attack surface that is associated with this vulnerability is reduced.

References

• cisco-sa-fmc-rce-NKhnULJh

Read on 2026-11-03T02:18:53.827Z under licence cve-terms-of-use@81bfa2f3 from https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/20xxx/CVE-2026-20131.json

Defensive techniques (MITRE D3FEND)

D3FEND maps these defensive techniques to the weakness (CWE) that NVD lists for this CVE, through the digital artifacts the weakness affects. D3FEND does not say they stop this vulnerability.

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