CVE-2026-20120: Cisco FTD ACL bypass vulnerability

Quick Answer

Cisco published a Medium-rated advisory that includes CVE-2026-20120, affecting Cisco Secure Firewall ASA / FTD under the live advisory's conditions. Cisco does not separately state a CVE-specific Security Impact Rating (SIR); Common Vulnerability Scoring System (CVSS) base 5.8 (Medium). Confirm the exact platform, release, feature, and exposure; preserve relevant evidence; then follow Cisco's CVE-specific First Fixed guidance. Cisco reported no public announcement or malicious use for this CVE at the last check. That status and absence from CISA KEV are time-bounded and do not prove exploitation has never occurred.

Last verified: 2026-09-17 UTC from Cisco's advisory and CSAF record. Recheck both the affected-products and fixed-software sections before a production change.

Context

Status At A Glance

Product scope	Cisco Secure Firewall ASA / FTD
CVE	CVE-2026-20120
TechGeeks response tier	P2 — review and schedule
Publication	New final Cisco advisory
First published	2026-09-16T16:00:00+00:00
Last updated	2026-09-16T16:00:00+00:00
Cisco advisory SIR	Medium
CVE-specific Cisco SIR	Not separately stated
CVSS base score / severity	5.8 — Medium
CVSS vector	CVSS v3.1 — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
CISA KEV at last check	No — this is separate from Cisco severity and is not proof of no exploitation.
Cisco exploitation statement	The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerabilities that are described in this advisory.

What Happened

Multiple vulnerabilities in the access control list (ACL) Object Group Search (OGS) implementation of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass configured access controls. These vulnerabilities are due to a logic error in populating group access control policies (ACPs) with OGS configured. An attacker could exploit these vulnerabilities by sending traffic that should be blocked through the device. A successful exploit could allow the attacker to bypass access controls and reach devices in protected networks. Cisco has released software updates that address these vulnerabilities. There are no workarounds that address these vulnerabilities. This advisory is part of a group of advisories. For a complete list of the advisories and links to them, see Cisco Advance Notification for Publication of September 16, 2026, Security Advisories. In addition, for further documentation of improvements and fixes in Cisco Secure Firewall products, see Cisco Secure Firewall Adaptive Security Appliance Software, Secure Firewall Threat Defense Software, and Secure Firewall Management Center Software Hardening Release: September 2026.

Affected Scope

At the time of publication, these vulnerabilities affected Cisco devices if they were running a vulnerable release of Cisco Secure Firewall ASA Software or Cisco Secure FTD Software and had ACLs with OGS configured. For information about which Cisco software releases are vulnerable, see the Fixed Software section of this advisory. Determine the ACL OGS Configuration on a Device That Is Running Cisco Secure FTD Software To determine whether a device that is running Cisco Secure FTD Software is configured for ACLs with OGS, use the following steps in Cisco Secure Firewall Management Center (FMC) Software: Choose Objects > Object Management. Choose the object type (for example, Network). View the object groups that are listed. If no object groups are listed, the device is not affected by these vulnerabilities. Determine the ACL OGS Configuration on a Device That Is Running Cisco Secure Firewall ASA Software To determine whether a device that is running Cisco Secure Firewall ASA Software is configured for ACPs with OGS, use the CLI command show running-config object-group-search, as shown in the following example: ciscoasa# show running-config object-group-search object-group-search access-control If the output returns no listed object groups, the device is not affected by these vulnerabilities.

Match the exact hardware or virtual platform, installed train, patch level, enabled service, role, and management or data-plane exposure. A Cisco product-family name alone does not establish applicability.

Steps

What To Do Now

1. Confirm. Inventory Cisco Secure Firewall ASA / FTD and record platform, exact release, patch level, enabled feature, role, and exposure.
2. Preserve. Save UTC context plus off-device authentication, management, firewall, network, endpoint, and SIEM evidence before logs rotate or a disruptive change removes context.
3. Scope. Compare each asset with the live Cisco advisory, including configuration prerequisites and exclusions.
4. Reduce exposure. Cisco documents no workaround for this CVE. Use only supported exposure controls while preparing the permanent fix.
5. Remediate. Confirm the affected product, release, and configuration. Cisco provides no workaround; reduce exposure where operationally feasible. Enter the exact installed product, platform, and release in Cisco Software Checker and upgrade to the returned First Fixed release. The CVE-specific live advisory and Cisco Software Checker result control the First Fixed release; any combined hardening baseline is supplemental only.
6. Validate. Confirm the resulting version, service health, logging, expected access, an expected denial, failover or cluster state, and representative dependent workflows.
7. Escalate. If evidence or exposure creates concern, open incident response and Cisco TAC recovery work rather than treating patch completion as proof of trust.

Fixed Releases And Mitigation

Investigation And Recovery

Review management authentication, account and privilege changes, API and web requests, configuration changes, crashes or restarts, resource pressure, and relevant external network telemetry for the vulnerable period. Preserve original evidence and follow Cisco TAC or incident-response guidance for containment, credential rotation, trusted rebuild, or service restoration when findings warrant it.

Notes

Exploitation Evidence

Cisco's exact status at the last check: The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerabilities that are described in this advisory.

This CVE was not present in the TechGeeks CISA KEV snapshot at the last check. Cisco's 'not aware' statement and absence from KEV are time-bounded evidence, not claims that exploitation is impossible or has never happened. Severity and exploitation status remain separate signals.

Validation And Boundaries

This notice is documentation-backed. TechGeeks did not reproduce the exploit or independently test every fixed build. It does not prove that all members of the product family are affected, that the activity is widespread, that a clean indicator search excludes compromise, or that an update restored trust. Cisco's live advisory controls affected and fixed release information.

Related TechGeeks Resources

• TechGeeks Security Notice Center
• All Security Notices
• What to Do When a Device Hits CISA KEV
• Router CVE Exposure, Version, and Mitigation Checklist
• IoT Firmware Update and End-of-Support Checklist
• Live Protect and Runtime Vulnerability Shielding

References

• Cisco security advisory
• Cisco CSAF record
• Cisco September 16 publication notice
• NVD identifier record

Wrap-Up

Record whether CVE-2026-20120 applies. If it does, assign an owner and deadline appropriate to the Medium Cisco advisory SIR, preserve the evidence, complete Cisco's remediation, and document the validated result.

Correction policy: A material Cisco revision to scope, severity, exploitation status, workarounds, fixed software, or recovery guidance triggers an update and a new verification date.