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TI-2021-13779 Aliases CVE-2021-34781GHSA-cg69-5r4f-47q5

Cisco Firepower Threat Defense Software SSH Connections Denial of Service Vulnerability

Priority MEDIUM 46CWE-119Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
No fix listed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-119 and the CVSS impact.

Summary

A vulnerability in the processing of SSH connections for multi-instance deployments of Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on the affected device. This vulnerability is due to a lack of proper error handling when an SSH session fails to be established. An attacker could exploit this vulnerability by sending a high rate of crafted SSH connections to the instance. A successful exploit could allow the attacker to cause resource exhaustion, which causes a DoS condition on the affected device. The device must be manually reloaded to recover.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.01402 72nd percentileScored 2026-11-07
Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
CiscoCisco Adaptive Security Appliance (ASA) Softwareall versions—No fix listedCNA
  • Cisco Adaptive Security Appliance (ASA) Software VendorCisco Affected all versions Fixed in — No fix listed CNA

CPE configurations NVD · 17

CPEVersionsRoleVendor
cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.3.0:*:*:*:*:*:*:*6.3.0VulnerableCisco
cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.4.0:*:*:*:*:*:*:*6.4.0VulnerableCisco
cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.4.0.13:*:*:*:*:*:*:*6.4.0.13VulnerableCisco
cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.5.0:*:*:*:*:*:*:*6.5.0VulnerableCisco
cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.6.0:*:*:*:*:*:*:*6.6.0VulnerableCisco
cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.7.0.3:*:*:*:*:*:*:*6.7.0.3VulnerableCisco
cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.7.1:*:*:*:*:*:*:*6.7.1VulnerableCisco
cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:7.0.0:*:*:*:*:*:*:*7.0.0VulnerableCisco
cpe:2.3:a:cisco:secure_firewall_threat_defense:*:*:*:*:*:*:*:*6.3.0 to before 6.4.0.13; 6.5.0 to before 6.6.5; 6.7.0 to before 6.7.0.3; 7.0.0 to before 7.0.1VulnerableCisco
cpe:2.3:a:cisco:sourcefire_defense_center:6.3.0:*:*:*:*:*:*:*6.3.0VulnerableCisco
  • cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.3.0:*:*:*:*:*:*:* Versions 6.3.0 Vulnerable ·Cisco
  • cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.4.0:*:*:*:*:*:*:* Versions 6.4.0 Vulnerable ·Cisco
  • cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.4.0.13:*:*:*:*:*:*:* Versions 6.4.0.13 Vulnerable ·Cisco
  • cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.5.0:*:*:*:*:*:*:* Versions 6.5.0 Vulnerable ·Cisco
  • cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.6.0:*:*:*:*:*:*:* Versions 6.6.0 Vulnerable ·Cisco
  • cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.7.0.3:*:*:*:*:*:*:* Versions 6.7.0.3 Vulnerable ·Cisco
  • cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.7.1:*:*:*:*:*:*:* Versions 6.7.1 Vulnerable ·Cisco
  • cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:7.0.0:*:*:*:*:*:*:* Versions 7.0.0 Vulnerable ·Cisco
  • cpe:2.3:a:cisco:secure_firewall_threat_defense:*:*:*:*:*:*:*:* Versions 6.3.0 to before 6.4.0.13; 6.5.0 to before 6.6.5; 6.7.0 to before 6.7.0.3; 7.0.0 to before 7.0.1 Vulnerable ·Cisco
  • cpe:2.3:a:cisco:sourcefire_defense_center:6.3.0:*:*:*:*:*:*:* Versions 6.3.0 Vulnerable ·Cisco
Show 7 more CPE
CPEVersionsRoleVendor
cpe:2.3:a:cisco:sourcefire_defense_center:6.4.0:*:*:*:*:*:*:*6.4.0VulnerableCisco
cpe:2.3:a:cisco:sourcefire_defense_center:6.4.0.13:*:*:*:*:*:*:*6.4.0.13VulnerableCisco
cpe:2.3:a:cisco:sourcefire_defense_center:6.5.0:*:*:*:*:*:*:*6.5.0VulnerableCisco
cpe:2.3:a:cisco:sourcefire_defense_center:6.6.0:*:*:*:*:*:*:*6.6.0VulnerableCisco
cpe:2.3:a:cisco:sourcefire_defense_center:6.7.0.3:*:*:*:*:*:*:*6.7.0.3VulnerableCisco
cpe:2.3:a:cisco:sourcefire_defense_center:6.7.1:*:*:*:*:*:*:*6.7.1VulnerableCisco
cpe:2.3:a:cisco:sourcefire_defense_center:7.0.0:*:*:*:*:*:*:*7.0.0VulnerableCisco
  • cpe:2.3:a:cisco:sourcefire_defense_center:6.4.0:*:*:*:*:*:*:* Versions 6.4.0 Vulnerable ·Cisco
  • cpe:2.3:a:cisco:sourcefire_defense_center:6.4.0.13:*:*:*:*:*:*:* Versions 6.4.0.13 Vulnerable ·Cisco
  • cpe:2.3:a:cisco:sourcefire_defense_center:6.5.0:*:*:*:*:*:*:* Versions 6.5.0 Vulnerable ·Cisco
  • cpe:2.3:a:cisco:sourcefire_defense_center:6.6.0:*:*:*:*:*:*:* Versions 6.6.0 Vulnerable ·Cisco
  • cpe:2.3:a:cisco:sourcefire_defense_center:6.7.0.3:*:*:*:*:*:*:* Versions 6.7.0.3 Vulnerable ·Cisco
  • cpe:2.3:a:cisco:sourcefire_defense_center:6.7.1:*:*:*:*:*:*:* Versions 6.7.1 Vulnerable ·Cisco
  • cpe:2.3:a:cisco:sourcefire_defense_center:7.0.0:*:*:*:*:*:*:* Versions 7.0.0 Vulnerable ·Cisco

Remediation

No fixed version listed by the sources yet.

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-34781
  2. 2026-10-03 Alias added: GHSA-cg69-5r4f-47q5

References

Advisory 1

  • TI-2018-00324 Cross-site request forgery in Cisco Firepower Management Center unknown CVSS 3.0HIGH 8.8
  • TI-2021-13760 Cisco Firepower Management Center Software Authenticated Directory Traversal Vulnerability CVSS 3.1HIGH 8.1
  • TI-2021-13754 Cisco Firepower Threat Defense Software Command Injection Vulnerabilities CVSS 3.1HIGH 7.8
  • TI-2021-13753 Cisco Firepower Threat Defense Software Command Injection Vulnerabilities CVSS 3.1HIGH 7.8
  • TI-2021-13762 Cisco Firepower Management Center Software Cross-Site Scripting and Open Redirect Vulnerabilities CVSS 3.1MEDIUM 6.1
  • TI-2021-13759 Cisco Firepower Threat Defense Software CLI Arbitrary File Write Vulnerability CVSS 3.1MEDIUM 6.0
See all 7 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences