Impacts widely deployed Cisco Secure FMC/FTD appliances; DoS can disrupt enterprise network security and management.
CVE-2026-20295
Remote DoS via sftunnel TLS memory exhaustion in Cisco Secure FMC/FTD
Is CVE-2026-20295 being exploited?
Not confirmed. CVE-2026-20295 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.
How severe is CVE-2026-20295?
CVE-2026-20295 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-2026-20295?
Not known from our data. No patch reference has been recorded for CVE-2026-20295, 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-2026-20295 affect?
CVE-2026-20295 affects Cisco Secure FMC Software, Cisco Secure FTD Software. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-20295?
Apply vendor updates ASAP or block/limit sftunnel traffic from untrusted networks.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Unauthenticated remote memory exhaustion via crafted sftunnel TLS frames causing device DoS and loss of management/traffic inspection.
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.