CVE Intelligence
High Cryptography

CVE-2026-20323 — Cisco Secure Firewall Management Center and Secure Firewall Threat Defense Software sftunnel Unauthorized Authentication Bypass Vulnerability

A vulnerability in the sftunnel inter-device communication protocol of Cisco Secure FMC Software and Cisco Secure FTD Software could allow an unauthenticated, adjacent attacker to impersonate the peer device and obtain access at the level of the manager role, which is equivalent to root. This vulnerability is due to improper management of the TLS certificate for the sftunnel management connection. An attacker could exploit this vulnerability by connecting to the sftunnel port using a crafted TLS certificate. A successful exploit could allow the attacker to become a registered sftunnel peer with root access. Note: The attack is successful only if the sftunnel connection is down or the attack can disrupt the sftunnel connection long enough to execute the attack.

Published Sep 16, 2026 · Updated Oct 15, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: cisco

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 0.1% (30-day exploitation probability)+0
  • Technical severity (high)+6

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
0.09%
ahead of 0% of scored CVEs · Oct 15, 2026
Affects
Cisco
Cisco Secure Firewall Management Center (FMC) and 1 more
CVSS base
8.3
High · 2 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation
None
none · proof-of-concept · active
Automatable
No
can an attacker script the kill-chain steps
Technical impact
Total
partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Cisco Cisco Secure Firewall Management Center (FMC), Cisco Cisco Secure Firewall Threat Defense (FTD) Software).
  2. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
  3. Search available logs for exploit probes matching the vulnerability class (cryptography), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Cisco Cisco Secure Firewall Management Center (FMC) version 7.4.2.4version 7.4.3version 7.6.3version 7.7.11version 7.6.4version 10.0.0version 7.4.4version 7.4.5
and 61 more version 7.0.9version 7.2.11version 7.7.12version 7.6.5version 7.4.6version 10.0.1version 7.4.7version 7.0.10version 7.0.0version 7.0.0.1version 7.0.1version 7.0.1.1version 7.0.2version 7.2.0version 7.0.2.1version 7.0.3version 7.2.0.1version 7.0.4version 7.2.1version 7.0.5version 7.3.0version 7.2.2version 7.3.1version 7.2.3version 7.2.3.1version 7.2.4version 7.0.6version 7.2.4.1version 7.2.5version 7.3.1.1version 7.4.0version 7.0.6.1version 7.2.5.1version 7.4.1version 7.2.6version 7.4.1.1version 7.0.6.2version 7.2.7version 7.2.5.2version 7.3.1.2version 7.2.8version 7.6.0version 7.4.2version 7.2.8.1version 7.0.6.3version 7.4.2.1version 7.2.9version 7.0.7version 7.7.0version 7.4.2.2version 7.2.10version 7.6.1version 7.4.2.3version 7.0.8version 7.6.2version 7.7.10version 7.2.10.1version 7.0.8.1version 7.6.2.1version 7.2.10.2version 7.7.10.1
Vulnerable CVE Program (cve.org) e CISA ADP
Cisco Cisco Secure Firewall Threat Defense (FTD) Software version 7.0.0version 7.0.0.1version 7.0.1version 7.0.1.1version 7.0.2version 7.2.0version 7.0.2.1version 7.0.3
and 53 more version 7.2.0.1version 7.0.4version 7.2.1version 7.0.5version 7.3.0version 7.2.2version 7.2.3version 7.3.1version 7.2.4version 7.0.6version 7.2.5version 7.2.4.1version 7.3.1.1version 7.4.0version 7.0.6.1version 7.2.5.1version 7.4.1version 7.2.6version 7.0.6.2version 7.4.1.1version 7.2.7version 7.2.5.2version 7.3.1.2version 7.2.8version 7.6.0version 7.4.2version 7.2.8.1version 7.0.6.3version 7.4.2.1version 7.2.9version 7.0.7version 7.7.0version 7.4.2.2version 7.2.10version 7.6.1version 7.4.2.3version 7.0.8version 7.6.2version 7.7.10version 7.7.11version 7.0.8.1version 7.6.2.1version 7.7.10.1version 7.4.2.4version 7.2.10.2version 7.4.3version 7.6.4version 10.0.0version 7.4.4version 7.0.9version 7.2.11version 7.4.7version 7.0.10
Vulnerable CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Adjacent
Attack complexity
High
Privileges required
None
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
8.3 CVSS 3.1 High 1.6 6.0 psirt@cisco.com via NIST National Vulnerability Database
8.3 CVSS 3.1 High — — cisco via CVE Program (cve.org) e CISA ADP
CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H (score shown at the top: psirt@cisco.com)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-295 · Improper Certificate Validation

Other CVEs with this weakness →

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Check TLS negotiations and unexpected certificates in the component’s traffic.
network IDS/IPS

Timeline

What happened to this CVE, newest first.

  • 2026
  • Affected products added · cisco/cisco secure firewall management center (fmc), cisco/cisco secure firewall threat defense (ftd) software
    Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
  • SSVC assessment updated
    Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 15, 2026
  • CVSS changed · 8.3
    Oct 15, 2026 · NIST National Vulnerability Database
  • Source status changed · → Awaiting Analysis
    Oct 15, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 15, 2026 · NIST National Vulnerability Database
  • CVE published
    Sep 16, 2026 · cisco

Source activity

Repeated readings are counted rather than listed.

  • 1× Official description updated · Oct 15, 2026 – Oct 15, 2026

References

1 on the record

Elsewhere on this site

Cisco
every CVE for this vendor
Cryptography
same class
CWE-295
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-76413 Cisco Secure Firewall Management Center Software Single Sign-On Token Forgery of Administrator Account Vulnerability 29d
  • CVE-2026-76412 Cisco Secure Firewall Management Center Software Authenticated Privilege Escalation to Root Vulnerability 29d
  • CVE-2026-20342 Cisco Secure Firewall Management Center Software Low Privileged Arbitrary File Download Vulnerability 29d
  • CVE-2026-20336 Cisco Secure Adaptive Security Appliance Software, Secure Firewall Threat Defense Software and Secure Firewall Management Center Software Hardening Release - Resource Lifetime Management Vulnerabilities 29d
  • CVE-2026-20340 Cisco Secure Firewall Management Center Software Deserialization Arbitrary Root Command Execution Vulnerability 29d
  • CVE-2026-20335 Cisco Secure Adaptive Security Appliance Software, Secure Firewall Threat Defense Software and Secure Firewall Management Center Software Hardening Release - Incorrect Calculation Vulnerabilities 29d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No fixed version, patch or mitigation documented.
  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-20323 is "Cisco Secure Firewall Management Center and Secure Firewall Threat Defense Software sftunnel Unauthorized Authentication Bypass Vulnerability", rated High. It affects Cisco Secure Firewall Management Center (FMC) (Cisco); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 8.3 describes technical severity. EPSS 0.09% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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