CVE-2026-20340: high-severity vulnerability in Cisco Secure Firewall Management Center (FMC)
Cisco Secure Firewall Management Center Software Deserialization Arbitrary Root Command Execution Vulnerability
Published · Updated
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21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 8.8epss 0.7%
A vulnerability in Cisco Secure FMC Software could allow an authenticated, remote attacker to execute arbitrary commands at the root privilege level.
This vulnerability is due to unsecured deserialization of web-management user-controlled data. An attacker could exploit this vulnerability by authenticating to the device and sending a crafted HTTP payload. A successful exploit could allow the attacker to save the crafted payload and then execute it on the underlying operating system as root.
To exploit this vulnerability, the attacker must have valid credentials for a user account with at least the role of Security Analyst (read-only).
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Affected products
Cisco · Cisco Secure Firewall Management Center (FMC)Related CVEs — Cisco Secure Firewall Management Center (FMC)
In the same product, most dangerous first.
CVE-2026-20079CRITICALCisco Secure Firewall Management Center Authentication Bypass Remote Code Execution VulnerabilityEPSS 88.7%KEVCVE-2026-20131CRITICALCisco Secure Firewall Management Center Software Remote Code Execution VulnerabilityEPSS 44.4%KEVCVE-2026-20316MEDIUMCisco Secure Firewall Management Center Software Static Credential VulnerabilityEPSS 35.1%KEVCVE-2026-20242CRITICALCisco Secure Firewall Management Center Software Java Deserialization Remote Code Execution VulnerabilityEPSS 0.9%CVE-2026-20343HIGHCisco Secure Firewall Management Center Software Information Disclosure and Disk Denial of Service VulnerabilityEPSS 0.7%CVE-2026-20324CRITICALCisco Secure Firewall Management Center sftunnel Root Arbitrary Code Exectution VulnerabilityEPSS 0.6%