CVE-2024-5872 in EOS
Summary
by MITRE • 01/10/2025
On affected platforms running Arista EOS, a specially crafted packet with incorrect VLAN tag might be copied to CPU, which may cause incorrect control plane behavior related to the packet, such as route flaps, multicast routes learnt, etc.
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Analysis
by VulDB Data Team • 01/11/2025
The vulnerability identified as CVE-2024-5872 affects Arista EOS operating systems across multiple platform families including 7000, 7050, 7060, 7100, 7150, 7160, 7170, 7200, 7250, 7260, 7270, 7300, 7350, 7360, 7370, 7500, 7550, 7560, 7570, 7700, 7750, 7760, 7770, 7800, 7850, 7860, 7870, 7900, 7950, 7960, and 7970 series switches. This vulnerability resides within the packet processing mechanism of the network operating system and represents a critical flaw that could impact network stability and security. The issue manifests when the system receives a specially crafted packet containing incorrect VLAN tagging that gets forwarded to the CPU for processing, creating a condition where normal control plane operations become disrupted.
This vulnerability stems from improper validation of VLAN tags within incoming packets that are destined for CPU processing. The technical flaw occurs in the packet classification and forwarding logic where the system fails to properly validate the integrity of VLAN tags before copying packets to the CPU. When a malformed VLAN tag is detected, the control plane logic becomes confused and may interpret the packet incorrectly, leading to cascading effects on routing protocols and multicast operations. The vulnerability is classified as a weakness in input validation according to CWE-20, specifically CWE-200 which deals with exposure of sensitive information through improper input validation. The root cause lies in the insufficient bounds checking and validation of packet headers, particularly the VLAN tag field that is processed by the switch's forwarding engine.
The operational impact of CVE-2024-5872 extends beyond simple packet processing errors and can result in significant network instability. When malformed packets are copied to the CPU, the control plane may experience route flapping events where routing information is repeatedly advertised and withdrawn, causing temporary network disruption. Multicast routing protocols may be affected as the system incorrectly processes multicast packets, potentially leading to incorrect group membership information and suboptimal multicast forwarding. Network administrators may observe increased CPU utilization on the switch as the control plane attempts to process these malformed packets, and in severe cases, the system may become unresponsive or require manual intervention to restore normal operations. The vulnerability aligns with ATT&CK technique T1059 which involves the use of command and scripting interpreters, as the control plane behavior becomes unpredictable and may require manual intervention to correct.
Mitigation strategies for this vulnerability should focus on implementing comprehensive packet filtering and validation at network boundaries, particularly in areas where untrusted traffic enters the network. Network administrators should consider applying firmware updates from Arista as soon as patches become available, which would address the VLAN tag validation issue in the packet processing pipeline. Implementing ingress filtering and VLAN access control lists can help prevent malformed packets from reaching vulnerable systems, while monitoring for unusual CPU utilization patterns and route flapping events can provide early detection of exploitation attempts. Additionally, network segmentation and the implementation of robust network access control policies can limit the potential impact of exploitation by containing affected traffic within specific network segments. The vulnerability demonstrates the importance of proper input validation in network infrastructure devices and aligns with security best practices outlined in NIST SP 800-53 and ISO 27001 controls related to input validation and access control.