CVE-2021-34790
MediumCVSS 4.7Exploitation Probability (EPSS)
Elevated risk63th percentile - higher than 63% of all known CVEs
Summary
Multiple vulnerabilities in the Application Level Gateway (ALG) for the Network Address Translation (NAT) feature of Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass the ALG and open unauthorized connections with a host behind the ALG. These vulnerabilities are publicly known as NAT Slipstreaming.
Risk Assessment
An attacker could bypass ALG protections and gain access to internal hosts, potentially leading to unauthorized access to network resources and network integrity compromise.
Recommendation
It is recommended to upgrade ASA/FTD software to patched versions and implement additional traffic filtering mechanisms.
Other vulnerabilities in Cisco Adaptive Security Appliance (ASA) Software
See all- CVE-2016-1367High
The DHCPv6 relay implementation in Cisco Adaptive Security Appliance (ASA) Software 9.4.1 allows remote attackers to cause a denial of service (device reload) via crafted DHCPv6 packets.
- CVE-2015-0677High
The XML parser in Cisco Adaptive Security Appliance (ASA) Software before version 8.4(7.28), 8.6(1.17), 9.0(4.33), 9.1(6), 9.2(3.4), and 9.3(3) is vulnerable to an attack that can lead to denial of service via a crafted XML document. This attack can result in VPN outages or device reloads.
- CVE-2015-0676High
The DNS implementation in Cisco Adaptive Security Appliance (ASA) Software before versions 7.2(5.16), 8.2(5.57), 8.3(2.44), 8.4(7.28), 8.5(1.24), 8.6(1.17), 8.7(1.16), 9.0(4.33), 9.1(6.1), 9.2(3.4), and 9.3(3) is vulnerable to man-in-the-middle attacks that can lead to denial of service by triggering DNS queries and sending crafted responses.
- CVE-2015-0675High
The failover IPsec implementation in Cisco Adaptive Security Appliance (ASA) Software before version 9.1(6), 9.2(3.3), and 9.3(3) does not properly validate failover communication messages, allowing remote attackers to reconfigure an ASA device.
- CVE-2014-2129High
The SIP inspection engine in Cisco Adaptive Security Appliance (ASA) Software before versions 8.2(5.48), 8.4(6.5), 9.0(3.1), and 9.1(2.5) allows remote attackers to cause a denial of service via crafted SIP packets.
- CVE-2014-2127High
Cisco Adaptive Security Appliance (ASA) Software versions before 8.2(5.48), 8.3 before 8.3(2.40), 8.4 before 8.4(7.9), 8.6 before 8.6(1.13), 9.0 before 9.0(4.1), and 9.1 before 9.1(4.3) does not properly process management-session information during privilege validation for SSL VPN portal connections. This allows remote authenticated users to gain privileges by establishing a Clientless SSL VPN session and entering crafted URLs.
- CVE-2014-2126High
Cisco Adaptive Security Appliance (ASA) Software versions before 8.2(5.47), 8.4(7.5), 8.7(1.11), 9.0(3.10), and 9.1(3.4) allows remote authenticated users to gain privileges by leveraging level-0 ASDM access.
- CVE-2025-20182High
A vulnerability in the Internet Key Exchange version 2 (IKEv2) protocol processing of Cisco Adaptive Security Appliance (ASA) Software, Cisco Firepower Threat Defense (FTD) Software, Cisco IOS Software, and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The issue is due to insufficient input validation when processing IKEv2 messages. Sending crafted IKEv2 traffic can cause the device to reload, resulting in a DoS condition.
- CVE-2024-20426High
A vulnerability in the Internet Key Exchange version 2 (IKEv2) protocol for VPN termination of 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. The issue is due to insufficient input validation. Sending crafted IKEv2 traffic can cause the device to reload, resulting in a DoS condition.
- CVE-2024-20382Medium
A vulnerability in the VPN web client services feature of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to conduct a cross-site scripting (XSS) attack against a browser accessing an affected device. The issue is due to improper validation of user-supplied input to application endpoints.
Original NVD description (English source)
Multiple vulnerabilities in the Application Level Gateway (ALG) for the Network Address Translation (NAT) feature of Cisco Adaptive Security Appliance (ASA) Software and Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass the ALG and open unauthorized connections with a host located behind the ALG. For more information about these vulnerabilities, see the Details section of this advisory. Note: These vulnerabilities have been publicly discussed as NAT Slipstreaming.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS