On 2026-03-19, CISA added CVE-2026-20131 (Cisco Secure Firewall Management Center (FMC)) to its Known Exploited Vulnerabilities (KEV) Catalog [2]. The vulnerability is listed in the catalog as "Cisco Secure Firewall Management Center (FMC) Software and Cisco Security Cloud Control (SCC) Firewall Management Deserialization of Untrusted Data Vulnerability" [2]. CISA requires remediation in accordance with vendor mitigation instructions; see the original text in the body for specific requirements [2].
Backfill: this event became public on Mar 19, 2026 and we added it on Nov 10, 2026. It is not a new event.
CISA Adds Cisco Secure Firewall Management Center (FMC) Vulnerability CVE-2026-20131 to Known Exploited Vulnerabilities Catalog
1 min read
- Disclosed
- Mar 19, 2026
- Published
- Nov 10, 2026
- Last updated
- Nov 8, 2026
- CVSS basis
- Our assessment
- 44.4%, higher than 99% of CVEs
- Exploitation and patch status
- ExploitedKEV
- Attack vector
- Vulnerability status
- Actor type
- Motivation
On this page
30-second summary
What happened
Who is affected
Industries mainly affected: Government, Cross-industry
What to do nowOur advice
CISA requires remediation in accordance with vendor mitigation instructions; see the original text in the body for specific requirements [2]
Timeline
Technical details
CISA KEV Listing Record
On 2026-03-19, CISA added CVE-2026-20131 to the catalog for Cisco Secure Firewall Management Center (FMC) [2].
Original Technical Description
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. [2]
Official Requirements
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. [2]
Individual Vulnerability Record
The U.S. National Vulnerability Database (NVD) provides an independent vulnerability record and description for CVE-2026-20131. [1]
References
Official / primary3
- [1]
“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-suppli”
- [2]
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