CVE-2024-20351 in Firepower Threat Defense Software
Summary
by MITRE • 10/23/2024
A vulnerability in the TCP/IP traffic handling function of the Snort Detection Engine of Cisco Firepower Threat Defense (FTD) Software and Cisco FirePOWER Services could allow an unauthenticated, remote attacker to cause legitimate network traffic to be dropped, resulting in a denial of service (DoS) condition.
This vulnerability is due to the improper handling of TCP/IP network traffic. An attacker could exploit this vulnerability by sending a large amount of TCP/IP network traffic through the affected device. A successful exploit could allow the attacker to cause the Cisco FTD device to drop network traffic, resulting in a DoS condition. The affected device must be rebooted to resolve the DoS condition.
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Analysis
by VulDB Data Team • 08/11/2025
The vulnerability identified as CVE-2024-20351 represents a critical denial of service weakness within Cisco Firepower Threat Defense software and FirePOWER Services platforms. This flaw exists in the TCP/IP traffic handling functions of the Snort Detection Engine, which serves as the core network traffic analysis component for these security solutions. The vulnerability stems from inadequate processing of TCP/IP network packets, creating a condition where legitimate network traffic becomes disrupted during normal operational periods. The affected systems are specifically designed to monitor and analyze network traffic for security threats while maintaining transparent network operations, making this weakness particularly dangerous as it directly impacts the availability of network services.
The technical exploitation mechanism of this vulnerability involves an attacker sending substantial volumes of TCP/IP traffic through the vulnerable Cisco FTD device. The flaw manifests when the system's Snort Detection Engine fails to properly manage or process incoming network packets, causing the device to drop legitimate traffic flows. This improper handling occurs at the network protocol level where TCP/IP packets are processed, leading to cascading failures in network connectivity. The vulnerability does not require authentication or special privileges to exploit, making it particularly dangerous as any remote attacker can potentially trigger the condition. The attack vector specifically targets the traffic processing capabilities of the device, leveraging the volume and characteristics of TCP/IP packets to overwhelm or confuse the processing logic.
The operational impact of CVE-2024-20351 extends beyond simple network disruption to potentially compromise enterprise security infrastructure. When exploited, the vulnerability creates a denial of service condition that affects the entire network segment monitored by the affected FTD device, potentially disrupting critical business operations and security monitoring capabilities. Organizations relying on Cisco Firepower solutions for network security may experience complete service outages requiring manual intervention and device rebooting to restore normal operations. The DoS condition affects the fundamental ability of the security appliance to perform its primary function of network traffic inspection and threat detection, creating a security gap during the outage period. This vulnerability directly impacts the availability and reliability of network security services, potentially leaving organizations vulnerable to other threats during the recovery phase.
Mitigation strategies for CVE-2024-20351 should prioritize immediate patching of affected systems through Cisco's official security advisories and software updates. Network administrators should implement traffic monitoring to detect unusual patterns that may indicate exploitation attempts, particularly focusing on sudden increases in TCP/IP traffic volumes. The implementation of rate limiting and traffic shaping policies can help reduce the impact of potential attacks by controlling the volume of traffic processed by the vulnerable system. Organizations should also consider deploying redundant security appliances to maintain network availability during patching operations or in case of successful exploitation. According to CWE classification, this vulnerability relates to CWE-400: Uncontrolled Resource Consumption, while the ATT&CK framework would categorize this under T1498: Network Denial of Service, highlighting the importance of both defensive measures and incident response planning. Regular network traffic analysis and baseline monitoring should be established to quickly identify when the system begins exhibiting symptoms of this vulnerability.