CVE entry · CVE-2026-20131
CVE-2026-20131: Cisco Secure Firewall Management Center (FMC) Software and Cisco Security Cloud Control (SCC) Firewall Management Deserialization of Untrusted Data Vulnerability
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.
- Actively exploited: added to CISA’s KEV catalog on March 19, 2026.
- Used by ransomware, according to CISA.
- Remediation deadline for US federal agencies: March 22, 2026.
Description from CISA’s KEV catalog.
What to do
- Check whether your estate includes Cisco Secure Firewall Management Center (FMC), including internet-facing devices.
- Apply the vendor’s patch or mitigations (references below). Failing that, isolate the product or stop using it, as CISA requires of US federal agencies.
- An exploited vulnerability has often been used before it was fixed: look for signs of compromise, especially on internet-facing devices.
References
- Vendor advisory or reference cited by CISA (sec.cloudapps.cisco.com)
- NVD entry (NIST)
- CISA KEV catalog
Other Cisco vulnerabilities
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Cisco Secure Email Gateway Relative Path Traversal Vulnerability
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Cisco Catalyst SD-WAN Manager Hex Encoding Vulnerability
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Cisco Identity Services Engine Incorrect Use of Privileged APIs Vulnerability
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Cisco Secure Email Gateway SQL Injection Vulnerability
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Cisco Firewall Management Center Authentication Bypass Using an Alternate Path or Channel Vulnerability
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Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) Heap Inspection Vulnerability