CVE-2024-20496 in SD-WAN vEdge Cloud
Summary
by MITRE • 09/25/2024
A vulnerability in the UDP packet validation code of Cisco SD-WAN vEdge Software could allow an unauthenticated, adjacent attacker to cause a denial of service (DoS) condition on an affected system.
This vulnerability is due to incorrect handling of a specific type of malformed UDP packet. An attacker in a machine-in-the-middle position could exploit this vulnerability by sending crafted UDP packets to an affected device. A successful exploit could allow the attacker to cause the device to reboot, resulting in a DoS condition on the affected system.
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Analysis
by VulDB Data Team • 09/29/2024
The vulnerability identified as CVE-2024-20496 represents a critical weakness in the UDP packet validation mechanisms of Cisco SD-WAN vEdge Software, specifically affecting devices operating within the software-defined wide area network infrastructure. This flaw manifests in the improper handling of certain malformed UDP packets, creating a pathway for malicious actors to disrupt network operations. The vulnerability is particularly concerning as it requires minimal privileges for exploitation, allowing unauthenticated attackers who are physically adjacent to the target system to potentially compromise network availability.
The technical root cause of this vulnerability lies in the insufficient validation of UDP packet headers and payload structures within the vEdge software's network processing stack. When the affected software receives malformed UDP packets containing specific patterns or irregularities in packet construction, the validation routines fail to properly sanitize or reject these inputs, leading to unexpected behavior within the network processing modules. This weakness directly maps to CWE-129, which addresses improper validation of input boundaries, and CWE-707, which covers improper neutralization of input during web application processing. The failure to properly validate UDP packet structures creates a condition where malformed data can propagate through the system's processing pipeline and trigger critical system failures.
The operational impact of this vulnerability extends beyond simple network disruption, as it enables attackers to induce complete system reboots through carefully crafted UDP packet sequences. This denial of service condition effectively renders the affected vEdge device non-functional, disrupting the SD-WAN connectivity and potentially cascading failures throughout the connected network infrastructure. The attack vector requires only adjacent network access, making it particularly dangerous in environments where physical security controls may be insufficient or where network segmentation is inadequate. Network administrators face the challenge of detecting such attacks, as they typically appear as legitimate network traffic patterns before causing system instability, aligning with ATT&CK technique T1499.002 for network disruption and T1071.004 for application layer protocol usage.
Mitigation strategies for CVE-2024-20496 should prioritize immediate software updates from Cisco to address the UDP validation flaws in the vEdge software. Network segmentation and access control measures should be implemented to limit physical access to affected devices, while network monitoring systems should be configured to detect unusual UDP packet patterns that may indicate exploitation attempts. The implementation of ingress filtering and rate limiting on UDP traffic can help reduce the impact of potential attacks, and regular network device firmware updates should be maintained as part of comprehensive security operations. Additionally, organizations should consider deploying network intrusion detection systems specifically configured to identify and alert on malformed UDP packet sequences that match the vulnerability characteristics, as outlined in the NIST Cybersecurity Framework's protective measures for system and information integrity.