High severity8.6NVD Advisory· Published Oct 27, 2021· Updated Aug 11, 2026

CVE-2021-40117

Description

A vulnerability in SSL/TLS message handler for Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability exists because incoming SSL/TLS packets are not properly processed. An attacker could exploit this vulnerability by sending a crafted SSL/TLS packet to an affected device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition.

AI Insight

LLM-synthesized narrative grounded in this CVE's description and references.

Affected products

Cisco Systems, Inc./Cisco Adaptive Security Appliance2 versions
cpe:2.3:a:cisco:adaptive_security_appliance:*:*:*:*:*:*:*:*+ 1 more
- cpe:2.3:a:cisco:adaptive_security_appliance:*:*:*:*:*:*:*:*range: <9.8.4.40
- cpe:2.3:o:cisco:adaptive_security_appliance_software:*:*:*:*:*:*:*:*range: >=9.9.0,<9.12.4.26
Cisco Systems, Inc./Secure Firewall Threat Defense
cpe:2.3:a:cisco:secure_firewall_threat_defense:*:*:*:*:*:*:*:*
Range: <6.2.3.17
Cisco Systems, Inc./Asa 5505 Firmware2 versions
cpe:2.3:o:cisco:asa_5505_firmware:009.009\(002.085\):*:*:*:*:*:*:*+ 1 more
- cpe:2.3:o:cisco:asa_5505_firmware:009.009\(002.085\):*:*:*:*:*:*:*
- cpe:2.3:o:cisco:asa_5505_firmware:009.014\(002.106\):*:*:*:*:*:*:*
Cisco Systems, Inc./Asa 5512 X Firmware2 versions
cpe:2.3:o:cisco:asa_5512-x_firmware:009.009\(002.085\):*:*:*:*:*:*:*+ 1 more
- cpe:2.3:o:cisco:asa_5512-x_firmware:009.009\(002.085\):*:*:*:*:*:*:*
- cpe:2.3:o:cisco:asa_5512-x_firmware:009.014\(002.106\):*:*:*:*:*:*:*
Cisco Systems, Inc./Asa 5515 X Firmware2 versions
cpe:2.3:o:cisco:asa_5515-x_firmware:009.009\(002.085\):*:*:*:*:*:*:*+ 1 more
- cpe:2.3:o:cisco:asa_5515-x_firmware:009.009\(002.085\):*:*:*:*:*:*:*
- cpe:2.3:o:cisco:asa_5515-x_firmware:009.014\(002.106\):*:*:*:*:*:*:*
Cisco Systems, Inc./Asa 5525 X Firmware2 versions
cpe:2.3:o:cisco:asa_5525-x_firmware:009.009\(002.085\):*:*:*:*:*:*:*+ 1 more
- cpe:2.3:o:cisco:asa_5525-x_firmware:009.009\(002.085\):*:*:*:*:*:*:*
- cpe:2.3:o:cisco:asa_5525-x_firmware:009.014\(002.106\):*:*:*:*:*:*:*
Cisco Systems, Inc./Asa 5545 X Firmware2 versions
cpe:2.3:o:cisco:asa_5545-x_firmware:009.009\(002.085\):*:*:*:*:*:*:*+ 1 more
- cpe:2.3:o:cisco:asa_5545-x_firmware:009.009\(002.085\):*:*:*:*:*:*:*
- cpe:2.3:o:cisco:asa_5545-x_firmware:009.014\(002.106\):*:*:*:*:*:*:*
Cisco Systems, Inc./Asa 5555 X Firmware2 versions
cpe:2.3:o:cisco:asa_5555-x_firmware:009.009\(002.085\):*:*:*:*:*:*:*+ 1 more
- cpe:2.3:o:cisco:asa_5555-x_firmware:009.009\(002.085\):*:*:*:*:*:*:*
- cpe:2.3:o:cisco:asa_5555-x_firmware:009.014\(002.106\):*:*:*:*:*:*:*
Cisco Systems, Inc./Asa 5580 Firmware2 versions
cpe:2.3:o:cisco:asa_5580_firmware:009.009\(002.085\):*:*:*:*:*:*:*+ 1 more
- cpe:2.3:o:cisco:asa_5580_firmware:009.009\(002.085\):*:*:*:*:*:*:*
- cpe:2.3:o:cisco:asa_5580_firmware:009.014\(002.106\):*:*:*:*:*:*:*
Cisco Systems, Inc./Asa 5585 X Firmware2 versions
cpe:2.3:o:cisco:asa_5585-x_firmware:009.009\(002.085\):*:*:*:*:*:*:*+ 1 more
- cpe:2.3:o:cisco:asa_5585-x_firmware:009.009\(002.085\):*:*:*:*:*:*:*
- cpe:2.3:o:cisco:asa_5585-x_firmware:009.014\(002.106\):*:*:*:*:*:*:*
Cisco Systems, Inc./Adaptive Security Appliance (ASA) Softwarellm-fuzzy
Cisco Systems, Inc./Firepower Threat Defense Softwarellm-fuzzy
Cisco Systems, Inc./Adaptive Security Appliance Cx Context Aware Security Softwarecpe-rescue
Range: n/a

Patches

Vulnerability mechanics

References

tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-dos-4ygzLKU9nvdVendor Advisory

News mentions

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