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CVE-2026-20329

Cisco Secure Adaptive Security Appliance Software, Secure Firewall Threat Defense Software and Secure Firewall Management Center Software Hardening Release - Exceptional Conditions Handling Vulnerabilities

Published: Sep 16, 2026Updated: Sep 18, 2026 Sources: CVE List NVDCWE-703
9.9CRITICAL
NVD MITRE
EPSS Score
0.4%
Top 61.9%
CISA KEV
Not in KEV
Exploits
0 Known
Remediation
No Fix Available
Self-Check
Not available

Description

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-2026-20329 are related to issues concerning improper handling of exceptional conditions that are grouped under the Common Weakness Enumeration (CWE) Pillar CWE-703.

In plain language

AI Act now

This is a critical flaw in Cisco firewall software; businesses using the affected products should treat it as urgent because a public exploit is available and no fix information is available.

Executive summary

CVE-2026-20329 is a CVSS 9.9 exceptional-conditions handling vulnerability (CWE-703) in Cisco firewall products that may enable a low-privileged attacker to compromise confidentiality, integrity, and availability across security scope boundaries.

If affected, business impact
Firewall management takeoverNetwork security disruptionSensitive data exposureConfiguration tamperingService outages

What to do now

  1. Inventory every installation of cisco secure firewall adaptive security appliance (asa) software, cisco secure firewall threat defense (ftd) software, and cisco secure firewall management center (fmc), including its installed version and who can log in.
  2. Restrict management access immediately to named administrators on trusted internal networks or a private management connection; remove unnecessary accounts and review administrator permissions.
  3. No fixed version has been announced in the available findings; check Cisco's advisory for CVE-2026-20329 and apply the exact fixed release as soon as Cisco publishes it.
  4. Review firewall and management-system logs for unexpected administrator logins, configuration exports or changes, new accounts, and unexplained restarts.
May need vendor / contractor work

CVSS Vector Breakdown

AV:NAC:LPR:LUI:NS:CC:HI:HA:H
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:LPrivileges Required
Low
UI:NUser Interaction
None
Scope
S:CScope
Changed
Impact
C:HConfidentiality
High
I:HIntegrity
High
A:HAvailability
High
Open in CVSS calculator →

Weaknesses

CWE-703

Affected Products

Cisco
commercial·USaka cisco systems, cisco systems inc.
Cisco Secure Firewall Adaptive Security Appliance (ASA) Software
Networking Infrastructure
Cisco Secure Firewall Management Center (FMC)
Networking Infrastructure
Cisco Secure Firewall Threat Defense (FTD) Software
Networking Infrastructure

Exploitability

0 exploit sources identified

Exploit details including PoC links, Metasploit modules, and scanner templates are available after registration.

View exploit details
Is your org exposed to CVE-2026-20329?Request an assessment to establish which checks are appropriate for your systems. Check my exposure

References

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-hardening-asaftdfmc-uvpPROhN
sec.cloudapps.cisco.com
News mentions
1

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