RCE in Cisco Firepower Extensible Operating System (Fxos)
CVE-2026-20099
A vulnerability in the web-based management interface of Cisco FXOS Software and Cisco UCS Manager Software could allow an authenticated, local attacker with administrative privileges to perform command injection attacks on an affected system and elevate privileges to root. This vulnerability is due to insufficient input validation of command arguments supplied by the user. An attacker could exploit this vulnerability by authenticating to a device and submitting crafted input to the affected command. A successful exploit could allow the attacker to execute arbitrary commands on the underlying operating system of the affected device with root-level privileges.
Vulnerability class: Command Injection (OS Command Injection)
EPSS: 0.006 (48.3th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 6.7 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H.
Affected products
- Cisco Firepower Extensible Operating System (Fxos) — versions 2.3.1.99, 2.3.1.56, 2.3.1.110
- Cisco Secure Firewall Adaptive Security Appliance (Asa) Software — versions 9.12.2, 9.12.1, 9.12.3
- Cisco Unified Computing System (Managed) — versions 4.0(4h), 4.1(1a), 4.0(1c)
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-20099?
- CVE-2026-20099 is a medium-severity vulnerability in Cisco Firepower Extensible Operating System (Fxos), classified under OS Command Injection. CVSS score: 6.7/10. Published 2026-02-25.
- How severe is CVE-2026-20099?
- Medium severity. CVSS v3 base score is 6.7 out of 10.