#VU123617 Deserialization of Untrusted Data in Cisco Secure Firewall Management Center (formerly Firepower Management Center, FMC) and Cisco Firewall Threat Defense (FTD) - CVE-2026-20131
Published: March 6, 2026 / Updated: March 19, 2026
Vulnerability identifier: #VU123617
Vulnerability risk: Critical
CVSSv4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:A/U:Red
CVE-ID: CVE-2026-20131
CWE-ID: CWE-502
Exploitation vector: Remote access
Exploit availability:
The vulnerability is being exploited in the wild
Vulnerable software:
Cisco Secure Firewall Management Center (formerly Firepower Management Center, FMC)
Cisco Firewall Threat Defense (FTD)
Cisco Secure Firewall Management Center (formerly Firepower Management Center, FMC)
Cisco Firewall Threat Defense (FTD)
Software vendor:
Cisco Systems, Inc
Cisco Systems, Inc
Description
The vulnerability allows a remote attacker to execute arbitrary code on the target system.
The vulnerability exists due to insecure input validation when processing serialized data in the web-based management interface. A remote non-authenticated attacker can send specially crafted serialized Java object to the web-based management interface of an affected device and execute arbitrary code on the target system with root privileges.
Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.
Remediation
Install updates from vendor's website.