CVE-2026-20242
CriticalCVSS 9.8Summary
Vulnerability in the External Database Access feature of Cisco Secure Firewall Management Center (FMC) allows an unauthenticated remote attacker to execute arbitrary commands as root. It is due to insecure deserialization of a user-supplied Java byte stream from a host in the external database access list.
Risk Assessment
An attacker controlling a host in the access list can gain full control of the device, potentially leading to complete network compromise.
Recommendation
Restrict access to the external database access list and apply patches provided by Cisco. If the management interface is not publicly accessible, the risk is reduced.
Other vulnerabilities in Cisco Secure Firewall Management Center
See all- CVE-2026-20079CriticalActively exploited
A vulnerability in the web interface of Cisco Secure Firewall Management Center (FMC) Software allows an unauthenticated, remote attacker to bypass authentication and execute script files to obtain root access to the underlying operating system. This is due to an improper system process created at boot time.
- CVE-2026-20044Medium
A vulnerability in the lockdown mechanism of Cisco Secure Firewall Management Center (FMC) Software could allow an authenticated, local attacker to perform arbitrary commands as root. This is due to insufficient restrictions on remediation modules while in lockdown mode. An attacker could exploit this by sending crafted input to the system CLI.
Original NVD description (English source)
A vulnerability in the External Database Access feature of Cisco Secure Firewall Management Center (FMC) Software could allow an unauthenticated, remote attacker to execute arbitrary commands as root on an affected device. This vulnerability is due to insecure deserialization of a user-supplied Java byte stream from a host that is configured in the external database access list. An attacker could exploit this vulnerability by sending a crafted, serialized Java byte stream to a specific TCP port of an affected device. A successful exploit could allow the attacker to execute arbitrary commands on the device and elevate privileges to root. Notes: This vulnerability can be exploited only by an attacker who has control of a host in the external database access list. If the FMC management interface does not have public internet access, the attack surface that is associated with this vulnerability is reduced.