{"id":"CVE-2026-20242","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-20242","summary":"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…","details":"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.\r\n\r\nThis 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.\r\nNotes:\r\n\r\nThis vulnerability can be exploited only by an attacker who has control of a host in the external database access list.\r\nIf the FMC management interface does not have public internet access, the attack surface that is associated with this vulnerability is reduced.","published":"2026-09-16T20:17:22.697","modified":"2026-09-16T20:17:22.697","cvss":{"score":9.8,"severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[],"fix":null,"references":[{"type":"WEB","url":"https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmc-javarce-y2NypXwk"}],"provenance":{"sources":["OSV.dev","NVD","FIRST.org (EPSS)"],"lastVerified":"2026-09-16T20:17:22.697"}}