Affects widely deployed Cisco Secure Firewall ASA/FTD — core perimeter devices. Unauthenticated remote DoS can disrupt enterprise networks; listed in CISA KEV so broad impact and urgent.
CVE-2026-20349
Unauthenticated remote heap issue in Cisco ASA/FTD causing device reload (DoS).
Is CVE-2026-20349 being exploited?
Yes. CVE-2026-20349 appears in CISA's Known Exploited Vulnerabilities catalog, which means exploitation in the wild has been confirmed and reported. Treat it as active rather than theoretical, and patch it ahead of higher-scoring vulnerabilities that carry no exploitation evidence.
How severe is CVE-2026-20349?
CVE-2026-20349 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-2026-20349?
Yes. A fix has been recorded for CVE-2026-20349. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-20349 affect?
CVE-2026-20349 affects Cisco Secure Firewall Adaptive Security Appliance (ASA), Cisco Secure Firewall Threat Defense (FTD). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-20349?
Apply Cisco mitigations/updates now; block management ports from Internet; follow CISA BOD 26-04.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Unauthenticated remote attacker can trigger heap inspection to reload devices, causing denial of service and network/perimeter outages.
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.