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CVE-2026-20131

CRITICAL severity · CVSS 10 · Insecure deserialization · actively exploited (CISA KEV)
10CVSS CRITICAL exploited ransomware
Actively exploited in the wild (CISA Known Exploited Vulnerabilities). Known use in ransomware campaigns. Added to KEV 2026-03-19. US federal agencies must patch by 2026-03-22.

Summary

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.

Impact & exploitability

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
Confidentiality impactHigh
Integrity impactHigh
Availability impactHigh
Exploit probability (EPSS)31%

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Affected products we track (1)

Secure Firewall Management Center (FMC) and Security Cloud Control (SCC) Firewall Management

Recommendation

This vulnerability is being actively exploited in the wild — patch affected products urgently. Open any affected product above for its exact safe version.

Additional information