---
title: "CVE-2026-20341: Cisco Secure FMC Software - Authentication Bypass"
description: "Cisco Secure FMC Software contains an insecure deserialization vulnerability in the sftunnel inter-device communication protocol, letting authenticated remote attackers gain root privileges by sending crafted RPCs, exploit requires valid administrative credentials."
url: https://panop.io/threat-heartbeat/CVE-2026-20341/
---

# CVE-2026-20341 Cisco Secure FMC Software - Authentication Bypass

Cisco Secure FMC Software contains an insecure deserialization vulnerability in the sftunnel inter-device communication protocol, letting authenticated remote attackers gain root privileges by sending crafted RPCs, exploit requires valid administrative credentials.

CVSS base score 9.1 /10

Critical

CISA KEV

Not listed

Public exploit

None known

Authentication

Required

EPSS

0.45% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-20341)

## Details

Type

Authentication Bypass

Impact

Privilege Escalation

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

Published

16 September 2026

Updated

15 October 2026

Weakness

[CWE-502](https://cwe.mitre.org/data/definitions/502.html)

## Vendor fix

Update to the latest available version of Cisco Secure FMC Software.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-20341](https://nvd.nist.gov/vuln/detail/CVE-2026-20341)
- [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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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

Panop answers these inside your environment, for this CVE and every other finding.

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