CVE-2026-20222: Cisco Secure Firewall ASA and FTD EIGRP Denial of Service Vulnerability
Tech GuruQuick Answer
CVE-2026-20222 affects vulnerable Cisco ASA and FTD releases with EIGRP enabled. An unauthenticated attacker on an adjacent network can send crafted routing updates at a high rate, causing a memory leak that eventually reloads the firewall. Cisco documents no workaround. Check the EIGRP configuration and obtain the installed platform's CVE-specific 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: Check vulnerable ASA/FTD releases with EIGRP enabled on an interface. The retained CLI check in Affected Scope explains how a network line establishes that configuration; combine it with the software-release check.
What could happen: An unauthenticated attacker on an adjacent network may send crafted EIGRP updates at a high rate, causing a memory leak that eventually reloads the firewall. This is a routing-protocol availability issue, not a stated remote code-execution flaw.
Not sure? Find the exact product, platform, and version in the management interface or CLI, then compare them with this CVE's affected-products section in Cisco's live advisory.
Status At A Glance
| Product scope | Cisco Secure Firewall ASA / FTD |
|---|---|
| CVE | CVE-2026-20222 |
| TechGeeks response tier | P1 — urgent |
| 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 | High |
| CVE-specific Cisco SIR | Not separately stated |
| CVSS base score / severity | 7.4 — High |
| CVSS vector | CVSS v3.1 — CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H |
| 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 vulnerability that is described in this advisory. |
What Happened
Improper resource management while processing EIGRP updates can leak memory on affected ASA and FTD devices. Repeated crafted updates from an adjacent attacker can eventually force an unexpected reload and interrupt service. This is an availability flaw, not a stated code-execution path. Cisco has released fixes; the configuration check below establishes the EIGRP condition only when paired with a vulnerable software release.
Affected Scope
This vulnerability affects Cisco devices if they are running a vulnerable release of Cisco Secure Firewall ASA Software or Cisco Secure FTD Software and have EIGRP enabled. For information about which Cisco software releases are vulnerable, see the Fixed Software section of this advisory. Determine the EIGRP Configuration To determine whether EIGRP is enabled on the device, use the show running-config router eigrp command on the device CLI. If that command produces output that includes at least one line that starts with network, as shown in the following example, EIGRP is enabled on at least one interface and the device is affected by this vulnerability: firewall# show running-config router eigrp router eigrp 1 network 10.0.200.0 255.255.255.0 If output is empty for this command or does not include a line that starts with network, EIGRP is not enabled globally or on any interface, and the device is not affected by this vulnerability.
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: Use Cisco Software Checker with the exact installed product, platform, and release to obtain the advisory-specific First Fixed release; the combined September hardening baseline is also recorded.
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-2026-20222. 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 vulnerability that is 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-2026-20222 applies. If it does, assign an owner and deadline appropriate to the High 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.
