Vulnerability · Published Sep 16, 2026 · Assigned by cisco
CVE-2026-20242Cisco Secure Firewall Management Center Software Java Deserialization Remote Code Execution Vulnerability
Critical 9.8
In plain English
A critical-severity unsafe deserialization in Cisco Secure Firewall Management Center (FMC) from Cisco. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.9% (higher than 60% of all known vulnerabilities).
Official description
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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Cisco | Cisco Secure Firewall Management Center (FMC) | 7.0.07.0.0.17.0.17.0.1.17.0.27.2.07.0.2.17.0.3 |
Weakness: CWE-502 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H