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CVE-2026-20341

Cisco Secure Firewall Management Center Software sftunnel Deserialization Root Command Execution Vulnerability

Published: Sep 16, 2026Updated: Sep 18, 2026 Sources: CVE List NVDCWE-502
9.1CRITICAL
NVD MITRE
EPSS Score
0.4%
Top 61.9%
CISA KEV
Not in KEV
Exploits
0 Known
Remediation
No Fix Available
Self-Check
Not available

Description

A vulnerability in the sftunnel inter-device communication protocol of Cisco Secure FMC Software could allow an authenticated, remote attacker to obtain root privileges. This vulnerability is due to unsecured deserialization of untrusted data over the sftunnel management connection. An attacker could exploit this vulnerability by sending crafted sftunnel remote procedure calls (RPCs). A successful exploit could allow the attacker to gain root privileges on a device that is running Cisco Secure FMC Software and its high-availability peer. To exploit this vulnerability, the attacker must have valid administrative credentials on a managed Cisco FTD device.

In plain language

AI Act now

Cisco Secure Firewall Management Center users should treat this as urgent: a public attack method can give someone with managed-device administrator access complete control of the system.

Executive summary

CWE-502 insecure deserialization in Cisco Secure Firewall Management Center sftunnel RPCs enables authenticated remote root command execution from valid administrative credentials on a managed Cisco FTD device.

If affected, business impact
Full firewall-management takeoverSecurity policy changesNetwork exposureHigh-availability peer compromiseOperational disruption

What to do now

  1. Confirm whether you run Cisco Secure Firewall Management Center and identify who has administrator access to managed Cisco FTD devices.
  2. Remove unnecessary administrator accounts, rotate credentials for former staff or vendors, and require strong multi-factor login protection where available.
  3. No fixed version has been published in the available findings; obtain Cisco’s remediation guidance and apply the vendor-provided fixed release as soon as one is available.
  4. Review management-system activity for unfamiliar administrator logins, configuration changes, or commands sent between paired systems.
May need vendor / contractor work

CVSS Vector Breakdown

AV:NAC:LPR:HUI:NS:CC:HI:HA:H
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:HPrivileges Required
High
UI:NUser Interaction
None
Scope
S:CScope
Changed
Impact
C:HConfidentiality
High
I:HIntegrity
High
A:HAvailability
High
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Weaknesses

CWE-502

Affected Products

Cisco
commercial·USaka cisco systems, cisco systems inc.
Cisco Secure Firewall Management Center (FMC)
Networking Infrastructure

Exploitability

0 exploit sources identified

Exploit details including PoC links, Metasploit modules, and scanner templates are available after registration.

View exploit details
Is your org exposed to CVE-2026-20341?Request an assessment to establish which checks are appropriate for your systems. Check my exposure

Attack Graph

Products CVE Techniques Tactics

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MITRE ATT&CK

3 techniques
Execution
Initial Access
View detailed technique mapping

References

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmc-mulivulns-4PsnFwvx
sec.cloudapps.cisco.com
News mentions
1

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