CVE-2026-20330

Cisco Secure Adaptive Security Appliance Software, Secure Firewall Threat Defense Software and Secure Firewall Management Center Software Hardening Release - Improper Neutralization Vulnerabilities

Public exploit available. Not confirmed exploited in the wild yet. No fix published yet.

CVSS 3.19.9Critical EPSS percentile24th0.3% chance in 30 days CISA KEVNot listedNo confirmed exploitation
Public exploit: 0 sources FixNone yetNo fix or workaround published

Published 2026-09-16Updated 2026-09-18Sources: CVE.org, NVD

NVD CVE.org

What to do

No fixed build or workaround is published yet. Limit exposure and watch for a patch.

Steps

Written by AI from the record

Check whether you run cisco secure firewall adaptive security appliance (asa) software, cisco secure firewall threat defense (ftd) software, or cisco secure firewall management center (fmc), and record each installed version.
Treat every deployed version as potentially affected until Cisco publishes affected-version details; no fixed version is currently available.
Restrict administrative access to trusted staff and networks, review administrator accounts, and remove any accounts that are no longer needed.
Ask your Cisco support contact for the hardening release or mitigation guidance for CVE-2026-20330, then schedule its deployment promptly.

May need vendor or contractor work

Is your organisation exposed?Request an assessment to establish which checks fit your systems.

What it is

From the CVE record

As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco Secure Adaptive Security Appliance Software, Cisco Secure Firewall Threat Defense Software and Cisco Secure Firewall Management Center Software engineering team has conducted a comprehensive internal security review. This review resulted in a software hardening release that addresses multiple internally discovered vulnerabilities.   The vulnerabilities tracked by CVE-2026-20330 are related to improper neutralization issues that are grouped under the Common Weakness Enumeration (CWE) Pillar CWE-707.

In plain language

Written by AI from the record

This is a critical security flaw in Cisco Secure Firewall ASA, FTD, and FMC software with a public exploit available, so affected businesses should act now even though Cisco has not published a fix.

CVE-2026-20330 is a CVSS 9.9 improper-neutralization issue (CWE-707) in Cisco Secure Firewall ASA, FTD, and FMC software that a logged-in attacker may exploit to compromise confidentiality, integrity, and availability across a security boundary.

If you're affected

Firewall administration takeover
Network security policy changes
Sensitive data exposure
Service disruption
Ransomware enablement

What is it

This flaw can let someone with access to the relevant administration functions make the software handle unsafe input incorrectly. Think of it as a security guard accepting a malformed access pass and then giving its holder more control than they should have over the building.

Who is affected

This matters to you if you use or run cisco secure firewall adaptive security appliance (asa) software, cisco secure firewall threat defense (ftd) software, or cisco secure firewall management center (fmc). The available information does not identify affected versions. It is a risk when an attacker already has a valid login.

How urgent is it

A public exploit is available, making this a red-priority issue for organizations running the affected Cisco software. CISA has not added it to its known-exploited-vulnerabilities list, but access to administrative systems should be tightened and vendor guidance pursued immediately.

What to do — in detail

Confirm exposure by inventorying all ASA, FTD, and FMC deployments, their software versions, management interfaces, administrator accounts, and network paths that can reach those interfaces. Cisco has not published an affected-version range, fixed version, branch-specific target, or upgrade path in the available findings; obtain the applicable hardening release or mitigation directly from Cisco before making version changes.

Until a vendor fix is available, limit management access to dedicated administrative networks and trusted accounts, enforce strong account controls, remove unused administrators, and review recent administrative changes for unexpected policy, configuration, or account modifications. There is no CISA KEV due date because this CVE is not listed in KEV. Monitor Cisco advisories for fixed-version guidance and investigate unexpected administrator logins or changes to firewall policy, device configuration, and management settings.

Technical context

Severity is CVSS 9.9 Critical (AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H). The reported weakness is CWE-707, improper neutralization. A public exploit is available, while CISA KEV does not list this CVE. EPSS is 0.3% at the 27th percentile with a flat trend; this is a prediction, not confirmation of exploitation. No patch or fixed-version information is available.

This is a general assessment based on public vulnerability data. It does not account for your specific infrastructure — when in doubt, consult a security specialist.

Exploitation

Where each signal puts this CVE on the scale from published to confirmed exploited.

EPSS24th

Public exploit

CISA KEV

Not in the catalog. CISA has not confirmed exploitation.

Public exploits

0 sources with a proof of concept or module.

Exploit links, PoCs and Metasploit modules after sign-in

EPSS

0.3% chance of exploitation activity in the next 30 days, which ranks it in the 24th percentile of scored CVEs.

Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.

Lifecycle

6 events over 2 days, from the signal feeds we watch.

2026-09-18Record updatedrecord updated, record updated
2026-09-16Publishedweakness classified, record updated

Affected products

Ciscocommercial · USaka cisco systems, cisco systems inc.

Technical detail

CVSS 3.1 vector

Open in the CVSS calculator

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

Scored 9.9 by NVD.

How it is reached

Attack Vector NetworkExploitable remotely over the network without any special conditions
Attack Complexity LowNo special conditions — the attack can be reliably reproduced
Privileges Required LowRequires basic user-level privileges
User Interaction NoneNo user interaction needed — fully automated exploitation

Scope

Scope ChangedThe exploit can affect other components (e.g. sandbox escape, host compromise from VM)

Impact if exploited

Confidentiality HighTotal information disclosure — all data in the component is compromised
Integrity HighTotal loss of integrity — attacker can modify any data in the component
Availability HighTotal denial of service — the component is completely unavailable