---
title: "CVE-2026-20329: Cisco Secure Firewall - Denial of Service"
description: "Cisco Secure Adaptive Security Appliance Software, Cisco Secure Firewall Threat Defense Software, and Cisco Secure Firewall Management Center Software contain an improper handling of exceptional conditions vulnerability (CWE-703), letting attackers cause potential denial of service or unexpected behavior, exploit requires triggering exceptional conditions."
url: https://panop.io/threat-heartbeat/CVE-2026-20329/
---

# CVE-2026-20329 Cisco Secure Firewall - Denial of Service

Cisco Secure Adaptive Security Appliance Software, Cisco Secure Firewall Threat Defense Software, and Cisco Secure Firewall Management Center Software contain an improper handling of exceptional conditions vulnerability (CWE-703), letting attackers cause potential denial of service or unexpected behavior, exploit requires triggering exceptional conditions.

CVSS base score 9.9 /10

Critical

CISA KEV

Not listed

Public exploit

Proof of concept available

Authentication

Required

EPSS

0.45% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-20329)

## Details

Type

Denial of Service

Impact

Denial Of Service

CVSS vector

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

Published

16 September 2026

Updated

15 October 2026

Weakness

[CWE-703](https://cwe.mitre.org/data/definitions/703.html)

## Vendor fix

Update to the latest software hardening release provided by Cisco.

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-2026-20329](https://nvd.nist.gov/vuln/detail/CVE-2026-20329)
- [https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-hardening-asaftdfmc-uvpPROhN](https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-hardening-asaftdfmc-uvpPROhN)

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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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