CVE-2021-40117
HighCVSS 8.6Exploitation Probability (EPSS)
Elevated risk72th percentile - higher than 72% of all known CVEs
Summary
A vulnerability in the SSL/TLS message handler of Cisco ASA and FTD Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS). The issue is due to improper processing of incoming SSL/TLS packets. Exploitation involves sending a crafted SSL/TLS packet.
Risk Assessment
Exploitation could cause device reload, leading to service disruption and potential downtime.
Recommendation
Update to patched software versions and implement network security controls to limit exposure.
Other vulnerabilities in Cisco ASA Software
See all- CVE-2016-6432High
A vulnerability in the Identity Firewall feature of Cisco ASA Software before version 9.6(2.1) could allow an unauthenticated, remote attacker to cause a reload of the affected system or to remotely execute code. The issue is due to a buffer overflow in the affected code area.
- CVE-2016-6431High
A vulnerability in the local Certificate Authority (CA) feature of Cisco ASA Software before version 9.6(1.5) could allow an unauthenticated, remote attacker to cause a reload of the affected system. The issue is due to improper handling of crafted packets during the enrollment operation.
- CVE-2014-3392High
The Clientless SSL VPN portal in Cisco ASA Software before version 8.2(5.51), 8.3(2.42), 8.4(7.23), 8.6(1.15), 9.0(4.24), 9.1(5.12), 9.2(2.8), and 9.3(1.1) allows remote attackers to obtain sensitive information from process memory or modify memory contents via crafted parameters.
- CVE-2014-3389High
The VPN implementation in Cisco ASA Software versions before 7.2(5.15), 8.2(5.51), 8.3(2.42), 8.4(7.23), 8.6(1.15), 9.0(4.24), 9.1(5.12), 9.2(2.6), and 9.3(1.1) does not properly implement a tunnel filter, allowing remote authenticated users to gain failover-unit access via crafted packets.
- CVE-2014-3388High
The DNS inspection engine in Cisco ASA Software 9.0 before 9.0(4.13), 9.1 before 9.1(5.7), and 9.2 before 9.2(2) allows remote attackers to cause a denial of service (device reload) via crafted DNS packets.
- CVE-2014-3387High
The SunRPC inspection engine in Cisco ASA Software before versions 7.2(5.14), 8.2(5.51), 8.3(2.42), 8.4(7.23), 8.5(1.21), 8.6(1.14), 8.7(1.13), 9.0(4.5), and 9.1(5.3) allows remote attackers to cause a denial of service (device reload) via crafted SunRPC packets.
- CVE-2014-3386High
The GPRS Tunneling Protocol (GTP) inspection engine in Cisco ASA Software before version 8.2(5.51), 8.4(7.15), 8.7(1.13), 9.0(4.8), and 9.1(5.1) allows remote attackers to cause a denial of service (device reload) via a crafted series of GTP packets.
- CVE-2014-3385High
A race condition in the Health and Performance Monitoring (HPM) for ASDM feature in Cisco ASA allows remote attackers to cause a denial of service by generating many half-open TCP connections simultaneously.
- CVE-2014-3384High
The IKEv2 implementation in Cisco ASA Software before versions 8.4(7.15), 8.6(1.14), 9.0(4.8), and 9.1(5.1) allows remote attackers to cause a denial of service by sending a crafted packet during tunnel creation.
- CVE-2014-3383High
The IKE implementation in the VPN component in Cisco ASA Software 9.1 before 9.1(5.1) allows remote attackers to cause a denial of service (device reload) via crafted UDP packets.
Original NVD description (English source)
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.

