Security Flaw in Cisco Secure FMC and FTD Software Affecting Device Communication
CVE-2026-20323

8.3HIGH

Key Information:

Vendor

Cisco
Status
Cisco Secure Firewall Management Center (fmc)
Cisco Secure Firewall Threat Defense (ftd) Software
Vendor
CVE Published:
16 September 2026

Badges

👾 Exploit Exists

What is CVE-2026-20323?

A flaw exists in the sftunnel inter-device communication protocol used by Cisco Secure FMC and FTD Software, which may allow an adjacent attacker to impersonate a peer device. This vulnerability arises from inadequate management of the TLS certificate associated with the sftunnel management connection. An attacker exploiting this issue can connect to the sftunnel port using a crafted TLS certificate, potentially gaining manager-level access rights. The exploit is contingent upon either the sftunnel connection being inactive or the attacker managing to disrupt the connection long enough to initiate the attack.

Affected Version(s)

Cisco Secure Firewall Management Center (FMC) 7.0.0

Cisco Secure Firewall Management Center (FMC) 7.0.0.1

Cisco Secure Firewall Management Center (FMC) 7.0.1

References

https://sec.cloudapps.cisco.com/security/center/content/C...

CVSS V3.1

Score:
8.3
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Adjacent Network
Attack Complexity:
High
Privileges Required:
None
User Interaction:
None
Scope:
Changed

Timeline

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

.