CVE-2026-20131
Cisco Secure Firewall Management Center (FMC) Software and Cisco Security Cloud Control (SCC) Firewall Management Deserialization of Untrust
Cisco Secure Firewall Management Center (FMC)
Exploitation status
CISA Known Exploited Vulnerabilities
Listed by CISA on 19 March 2026. US federal agencies were required to remediate it by 22 March 2026. CISA records this vulnerability as known to be used in ransomware campaigns.
EPSS — exploitation probability
FIRST puts the probability of exploitation activity in the next 30 days at 28.2%, which is higher than 97.9% of all scored vulnerabilities. EPSS is a forecast of activity, not a measure of severity, and it is rescored daily.
Frequently asked questions
Is CVE-2026-20131 being exploited by ransomware groups?
No ransomware group in this database is currently recorded as exploiting CVE-2026-20131.
What does CVE-2026-20131 affect?
CVE-2026-20131 affects Cisco Secure Firewall Management Center (FMC).
How severe is CVE-2026-20131?
EPSS puts the probability of exploitation in the next 30 days at 28.2%, higher than 97.9% of all scored vulnerabilities. It is listed in the CISA Known Exploited Vulnerabilities catalog, with a federal remediation deadline of 22 March 2026.
How should organisations respond to CVE-2026-20131?
Apply the vendor patch for Cisco Secure Firewall Management Center (FMC) as the first priority, and treat any internet-facing instance as the most urgent. Because this vulnerability is associated with ransomware activity, also review whether the affected systems were reachable before patching, rather than assuming that patching alone closes the incident.