CVE-2019-19043 in Linux
Summary
by MITRE
A memory leak in the i40e_setup_macvlans() function in drivers/net/ethernet/intel/i40e/i40e_main.c in the Linux kernel through 5.3.11 allows attackers to cause a denial of service (memory consumption) by triggering i40e_setup_channel() failures, aka CID-27d461333459.
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Analysis
by VulDB Data Team • 08/06/2025
The vulnerability identified as CVE-2019-19043 represents a critical memory management flaw within the Linux kernel's networking subsystem, specifically affecting the i40e driver responsible for Intel Ethernet network adapters. This memory leak occurs within the i40e_setup_macvlans() function located in the drivers/net/ethernet/intel/i40e/i40e_main.c source file, impacting all Linux kernel versions through 5.3.11. The flaw manifests when the i40e_setup_channel() function fails during operation, creating a condition where allocated memory resources are not properly released back to the system. This particular vulnerability falls under the CWE-401 vulnerability category, which specifically addresses memory leaks in software systems, making it a direct threat to system stability and resource availability. The issue is particularly concerning as it enables attackers to consume system memory resources through controlled triggering of the failure condition, ultimately leading to denial of service scenarios.
The technical implementation of this vulnerability exploits the improper memory management within the driver's channel setup functionality. When i40e_setup_channel() encounters failure conditions during its execution, the i40e_setup_macvlans() function fails to properly clean up previously allocated memory structures. This failure creates a gradual accumulation of unreleased memory segments that persist in the system's memory pool, effectively reducing available resources for legitimate system operations. The memory leak operates through a cascading failure mechanism where each invocation of the problematic code path results in additional memory consumption without corresponding deallocation. This behavior is particularly dangerous in production environments where continuous network operations might inadvertently trigger the failure condition, leading to progressive system degradation and eventual system crashes or unresponsiveness.
The operational impact of this vulnerability extends beyond simple resource exhaustion, as it can be systematically exploited to cause sustained denial of service conditions across network infrastructure. Attackers can repeatedly trigger the i40e_setup_channel() failure scenario to continuously consume system memory, potentially affecting not just individual network interfaces but entire system stability. The vulnerability affects systems running vulnerable kernel versions and can be particularly devastating in high-availability environments or mission-critical infrastructure where network connectivity is essential. The memory consumption pattern creates a predictable degradation that can be monitored and exploited for sustained disruption of network services, making this vulnerability attractive to threat actors seeking to compromise system availability. This type of attack aligns with ATT&CK technique T1499.004, which focuses on network denial of service attacks through resource exhaustion.
Mitigation strategies for CVE-2019-19043 primarily involve immediate kernel version updates to patched releases that address the memory leak in the i40e driver implementation. System administrators should prioritize upgrading to kernel versions 5.4.0 or later where the vulnerability has been resolved through proper memory management fixes in the i40e_setup_macvlans() function. Additionally, monitoring network traffic patterns for unusual channel setup failures can help detect exploitation attempts, though this approach is reactive rather than preventive. The patch implementation addresses the root cause by ensuring proper memory deallocation when i40e_setup_channel() fails, preventing the accumulation of leaked memory segments. Organizations should also implement network segmentation and access controls to limit potential attack surface, while maintaining regular vulnerability assessments to identify similar memory management flaws in other kernel subsystems. System hardening practices including disabling unnecessary network features and implementing proper resource limits can further reduce the impact of such vulnerabilities, as outlined in the NIST Cybersecurity Framework for managing kernel-level security risks.