CVE-2026-20121: Cisco FTD Bypass Access List
Tech GuruQuick Answer
With Object Group Search (OGS) configured on a vulnerable Cisco ASA or FTD release, CVE-2026-20121 may let unauthenticated remote traffic bypass access controls and reach protected devices. Cisco describes it alongside CVE-2026-20120 without establishing a separate mechanism for each. There is no workaround; use CVE-2026-20121 when obtaining the installed platform's First Fixed release from Software Checker.
Fix Or Immediate Action
What to do now: 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.
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
Scope And Impact In Plain Language
Who should check: Anyone who manages Cisco Secure Firewall ASA / FTD.
When this applies: Both a vulnerable ASA/FTD release and ACLs using Object Group Search (OGS) are required. Use the retained FMC object-group inspection or ASA CLI check in Affected Scope, then compare the installed release with this CVE's live advisory.
What could happen: An attacker may be able to bypass a security rule and reach data, systems, or administrative functions that should be blocked.
Not sure? Record the appliance's product, platform, release, and OGS configuration. Cisco describes CVE-2026-20120 and CVE-2026-20121 together, but the 5.3 score and vector on this page belong to CVE-2026-20121; use its identifier when recording applicability and remediation.
Status At A Glance
| Product scope | Cisco Secure Firewall ASA / FTD |
|---|---|
| CVE | CVE-2026-20121 |
| 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 | 5.3 — Medium |
| CVSS vector | CVSS v3.1 — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N/E:P/RL:O/RC:C |
| 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
The shared Cisco advisory attributes these OGS bypasses to a logic error when populating group access control policies. An attacker can send traffic that the configured rules should block, potentially reaching protected network devices. That shared account does not establish a distinct exploit mechanism for CVE-2026-20121. Its 5.3 score and vector are retained separately in the status table. Cisco provides software fixes, but no workaround.
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
- Confirm. Inventory Cisco Secure Firewall ASA / FTD and record platform, exact release, patch level, enabled feature, role, and exposure.
- Preserve. Save UTC context plus off-device authentication, management, firewall, network, endpoint, and SIEM evidence before logs rotate or a disruptive change removes context.
- Scope. Compare each asset with the live Cisco advisory, including configuration prerequisites and exclusions.
- Reduce exposure. Cisco documents no workaround for this CVE. Use only supported exposure controls while preparing the permanent fix.
- Remediate. Follow the CVE-specific method and release guidance under Permanent Fix below.
- Validate. Confirm the resulting version, service health, logging, expected access, an expected denial, failover or cluster state, and representative dependent workflows.
- 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
Permanent Fix
Cisco method: Obtain the advisory-specific First Fixed result for the installed ASA/FTD platform and release from Cisco Software Checker. Record any Combined First Fixed recommendation separately; no combined build table is reproduced on this page.
No compact per-CVE fixed-release table is reproduced here because Cisco may use different First Fixed values by CVE and software train. Use this CVE's live advisory table or Cisco Software Checker; do not infer a fixed release from a combined hardening baseline or another Cisco notice.
Workaround Or Temporary Mitigation
No vendor workaround is documented for CVE-2026-20121. Use supported exposure controls only as temporary risk reduction while preparing the permanent software fix.
Important boundary: A workaround, ACL, exposure reduction, or service restriction can reduce risk while the update is prepared, but it does not patch the vulnerable code, prove every attack path is closed, or erase an earlier compromise.
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
Wrap-Up
Record whether CVE-2026-20121 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.
