---
title: "CVE-2026-20295: Cisco Secure FMC & FTD Software - Denial of Service"
description: "Cisco Secure FMC Software and Cisco Secure FTD Software contain a denial of service vulnerability caused by improper memory management during sftunnel TLS connection setup, letting unauthenticated remote attackers exhaust device memory by sending crafted TLS frames."
url: https://panop.io/threat-heartbeat/CVE-2026-20295/
---

# CVE-2026-20295 Cisco Secure FMC & FTD Software - Denial of Service

Cisco Secure FMC Software and Cisco Secure FTD Software contain a denial of service vulnerability caused by improper memory management during sftunnel TLS connection setup, letting unauthenticated remote attackers exhaust device memory by sending crafted TLS frames.

CVSS base score 8.6 /10

High

CISA KEV

Not listed

Public exploit

None known

Authentication

Not required

EPSS

0.55% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-20295)

## Details

Type

Denial of Service

Impact

Denial Of Service

CVSS vector

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

Published

16 September 2026

Updated

15 October 2026

Weakness

[CWE-789](https://cwe.mitre.org/data/definitions/789.html)

## Vendor fix

Update to the latest available version of Cisco Secure FMC Software and Cisco Secure FTD 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-2026-20295](https://nvd.nist.gov/vuln/detail/CVE-2026-20295)
- [https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmcftd-sftun-multivulns-WGVHOrN3](https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmcftd-sftun-multivulns-WGVHOrN3)

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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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