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CVE-2026-20336

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

Published: Sep 16, 2026Updated: Sep 18, 2026 Sources: CVE List NVDCWE-664
8.8HIGH
NVD MITRE
EPSS Score
0.2%
Top 90.2%
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-2026-20336 are related to issues concerning improper control of a resource through its lifetime that are grouped under the Common Weakness Enumeration (CWE) Pillar CWE-664.

In plain language

AI Act now

Businesses using affected Cisco firewall or firewall-management software should treat this as urgent because public attack code is available and no fixed version is yet listed.

Executive summary

CVE-2026-20336 is a high-severity, unauthenticated adjacent-network resource-lifetime management vulnerability group affecting Cisco ASA, FTD, and FMC.

If affected, business impact
Firewall takeoverNetwork traffic exposureSecurity-policy changesService disruptionRansomware risk

What to do now

  1. Ask your IT provider to identify 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).
  2. Check Cisco’s security advisory and support portal for the affected-release list; the findings do not provide one.
  3. No fixed version is currently available in the findings, so ask Cisco or your support provider for the hardening-release version and deployment plan.
  4. Until Cisco provides the update, restrict management and firewall access to trusted, separated network segments and remove unnecessary access paths.
May need vendor / contractor work

CVSS Vector Breakdown

AV:AAC:LPR:NUI:NS:UC:HI:HA:H
Exploitability
AV:AAttack Vector
Adjacent
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:HConfidentiality
High
I:HIntegrity
High
A:HAvailability
High
Open in CVSS calculator →

Weaknesses

CWE-664

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-2026-20336?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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