Affects widely deployed Cisco Secure Firewall ASA/FTD; unauthenticated remote DoS against perimeter firewalls can disrupt enterprise networks and services.
CVE-2026-20249
Cisco ASA/FTD IKEv2 certificate auth logic allows remote DoS (device reload).
Is CVE-2026-20249 being exploited?
Not confirmed. CVE-2026-20249 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.40% probability of exploitation in the next 30 days.
How severe is CVE-2026-20249?
CVE-2026-20249 is rated High with a CVSS score of 8.6. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-20249?
Not known from our data. No patch reference has been recorded for CVE-2026-20249, which is not the same as no patch existing — a fix may have shipped without a tagged reference, or after this record was written. The vendor advisory is the only authority on whether a fix exists, and mitigations may be available regardless.
What does CVE-2026-20249 affect?
CVE-2026-20249 affects Cisco Secure Firewall Adaptive Security Appliance (ASA) Software, Cisco Secure Firewall Threat Defense (FTD) Software. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-20249?
Apply Cisco advisory mitigations and updates ASAP; restrict/inspect IKEv2 from untrusted networks.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Unauthenticated remote attacker can send a crafted IKEv2 certificate to crash IKEv2 process and reload the device, causing network/perimeter DoS.
Immediate action required
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As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.