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CVE-2026-20131 Cisco CVE debrief

CVE-2026-20131 is a Cisco Secure Firewall Management Center (FMC) and Cisco Security Cloud Control (SCC) Firewall Management deserialization of untrusted data vulnerability. CISA added it to the Known Exploited Vulnerabilities catalog on 2026-03-19 and marked known ransomware campaign use, with a remediation due date of 2026-03-22. Treat this as an active exposure requiring immediate defensive review of any affected Cisco management deployment.

Vendor
Cisco
Product
Secure Firewall Management Center (FMC)
CVSS
Unknown
CISA KEV
Listed
Original CVE published
2026-03-19
Original CVE updated
2026-03-19
Advisory published
2026-03-19
Advisory updated
2026-03-19

Who should care

Cisco FMC and SCC Firewall Management owners, firewall/security platform administrators, vulnerability management teams, SOC analysts, incident responders, and cloud/security operations teams responsible for Cisco-managed firewall infrastructure.

Technical summary

The supplied source corpus identifies CVE-2026-20131 as a deserialization of untrusted data issue in Cisco Secure Firewall Management Center (FMC) Software and Cisco Security Cloud Control (SCC) Firewall Management. The CISA KEV entry indicates the vulnerability is known exploited and notes known ransomware campaign use. No CVSS score or exploit mechanics were provided in the supplied record, so remediation should be driven by the KEV status and Cisco's vendor guidance.

Defensive priority

Urgent. Because CISA has placed this CVE in KEV and set a due date of 2026-03-22, prioritize inventory, mitigation, and exposure reduction immediately.

Recommended defensive actions

  • Identify every Cisco Secure Firewall Management Center (FMC) and Cisco Security Cloud Control (SCC) Firewall Management instance in your environment.
  • Follow Cisco's security advisory and vendor mitigation guidance referenced by CISA in the KEV record.
  • Apply mitigations as soon as practical; if mitigations are unavailable, follow CISA's guidance to discontinue use of the product.
  • For cloud services, follow applicable BOD 22-01 guidance as referenced in the CISA KEV entry.
  • Validate whether any exposed management interfaces, integrations, or administrative access paths can be reduced while remediation is underway.
  • Monitor Cisco and CISA updates for any additional vendor instructions or remediation steps.

Evidence notes

Source corpus is limited to the CISA KEV record and official reference links. The KEV entry lists vendorProject Cisco, product Secure Firewall Management Center (FMC), vulnerability name 'Cisco Secure Firewall Management Center (FMC) Software and Cisco Security Cloud Control (SCC) Firewall Management Deserialization of Untrusted Data Vulnerability,' dateAdded 2026-03-19, dueDate 2026-03-22, and knownRansomwareCampaignUse 'Known.' The KEV notes explicitly reference a Cisco Security Advisory URL and the NVD detail page. No CVSS score or further technical detail was supplied in the record.

Official resources

Publicly disclosed through CISA's Known Exploited Vulnerabilities catalog on 2026-03-19, with the source record also pointing to Cisco's security advisory and NVD detail page.