CVE-2026-20295 Cisco Secure FMC & FTD Software - Denial of Service

Cisco Secure FMC Software and Cisco Secure FTD Software contain a denial of service vulnerability caused by improper memory management during sftunnel TLS connection setup, letting unauthenticated remote attackers exhaust device memory by sending crafted TLS frames.

CVSS base score 8.6 /10
High
CISA KEV
Not listed
Public exploit
None known
Authentication
Not required
EPSS
0.55% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Denial of Service
Impact
Denial Of Service
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Published
16 September 2026
Updated
15 October 2026
Weakness
CWE-789

Vendor fix

Update to the latest available version of Cisco Secure FMC Software and Cisco Secure FTD Software.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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