# CVE-2026-20341: Cisco Secure FMC Software unsecured deserialization in sftunnel

Source: https://junglewise.ai/threats/cve-2026-20341-cisco-secure-fmc-software-unsecured-deserialization-in-sftunnel  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-16. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-20341 · Severity: critical · CVSS 9.1 · Published 2026-09-16

Cisco Secure Firewall Management Center (FMC) contains a vulnerability in its inter-device communication protocol that allows authenticated attackers with administrative access to a managed Firepower Threat Defense device to execute arbitrary commands as root on the FMC and its high-availability peer. An attacker who compromises an FTD device with admin credentials could escalate privileges to control the entire firewall management infrastructure, leading to potential takeover of all protected networks and data.

Technologies: [Cisco Secure Firewall Management Center](https://junglewise.ai/threats/technologies/secure-firewall-management-center). Vendors: [Cisco](https://junglewise.ai/threats/vendors/cisco).

## Quick answers

**Is CVE-2026-20341 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-20341 being exploited in the wild.

**How severe is CVE-2026-20341?** Critical severity, with a CVSS score of 9.1, published 16 September 2026.

**Which products and versions are affected?** Cisco Secure Firewall Management Center.

**Is there a fix for CVE-2026-20341?** A patch was published on 2026-09-16: Cisco released software updates Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-20341 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-20341?** Check whether you run Cisco Secure Firewall Management Center. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

This vulnerability exists in the sftunnel inter-device communication protocol and is caused by insecure deserialization of untrusted data. An authenticated attacker with valid administrative credentials on a managed Cisco FTD device can send crafted sftunnel remote procedure calls (RPCs) over the management connection to exploit this flaw. The vulnerability is reachable over the network (AV:N) with low attack complexity (AC:L) and high privileges required (PR:H). A successful exploit grants root-level command execution on both the primary FMC and its high-availability peer. Cisco has released software updates to address this vulnerability and no workarounds are available.

## Affected products

- Cisco Secure Firewall Management Center

## Timeline

- 2026-09-16: disclosed
- 2026-09-16: patched: Cisco released software updates

## References

- [https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmc-mulivulns-4PsnFwvx](https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmc-mulivulns-4PsnFwvx)

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- [Cisco Secure FMC privilege escalation in remote diagnostics debugger](https://junglewise.ai/threats/cve-2026-76412-cisco-secure-fmc-privilege-escalation-in-remote-diagnostics)
- [Cisco Secure Firewall software resource lifecycle vulnerability](https://junglewise.ai/threats/cve-2026-20336-cisco-secure-firewall-software-resource-lifecycle-vulnerability)
- [Cisco Secure FMC and FTD sftunnel authentication bypass](https://junglewise.ai/threats/cve-2026-20323-cisco-secure-fmc-and-ftd-sftunnel-authentication-bypass)
- [Cisco Secure FMC and FTD memory exhaustion in sftunnel](https://junglewise.ai/threats/cve-2026-20295-cisco-secure-fmc-and-ftd-memory-exhaustion-in-sftunnel)