CVE-2019-19068 in Linux
Summary
by MITRE
A memory leak in the rtl8xxxu_submit_int_urb() function in drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c in the Linux kernel through 5.3.11 allows attackers to cause a denial of service (memory consumption) by triggering usb_submit_urb() failures, aka CID-a2cdd07488e6.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 02/23/2024
The vulnerability identified as CVE-2019-19068 represents a critical memory management flaw within the Linux kernel's wireless driver subsystem, specifically affecting the Realtek rtl8xxxu wireless network adapter drivers. This issue resides in the rtl8xxxu_submit_int_urb() function located in drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c file, where the kernel fails to properly handle memory allocation and deallocation during USB transfer operations. The vulnerability affects all Linux kernel versions up to and including 5.3.11, making it a widespread concern for systems utilizing Realtek wireless adapters. The flaw manifests when the usb_submit_urb() function encounters failures during USB transfer submission, creating a scenario where allocated memory resources are not properly released back to the system, leading to progressive memory consumption over time.
The technical implementation of this vulnerability stems from improper error handling within the wireless driver's interrupt urb submission mechanism. When usb_submit_urb() fails to submit an interrupt transfer, the rtl8xxxu_submit_int_urb() function does not adequately clean up previously allocated memory structures, resulting in memory leaks that accumulate with each failed USB transfer attempt. This memory leak behavior directly violates the fundamental principles of resource management and can be exploited by malicious actors to systematically consume system memory resources. The vulnerability operates at the kernel level, making it particularly dangerous as it can affect the entire system's stability and performance, potentially leading to complete system hangs or crashes.
From an operational perspective, this vulnerability presents a significant denial of service threat that can be easily exploited by remote attackers without requiring elevated privileges. Attackers can trigger the memory leak condition by repeatedly causing USB transfer failures, either through network interference, physical manipulation of wireless hardware, or by crafting specific network traffic patterns that force the driver to fail in submitting interrupt transfers. The impact extends beyond simple service disruption, as continuous memory consumption can degrade system performance, cause applications to crash, and eventually lead to system instability or complete system failure. This vulnerability particularly affects systems running Linux kernel versions 5.3.11 and earlier, making it a critical concern for enterprise environments and embedded systems that rely on Realtek wireless adapters for network connectivity.
The mitigation strategy for CVE-2019-19068 involves immediate kernel updates to versions 5.3.12 and later where the memory leak has been addressed through proper error handling and resource cleanup mechanisms. System administrators should prioritize patching affected systems, particularly those in production environments where wireless connectivity is critical. Additionally, monitoring for unusual memory consumption patterns and implementing automated alerting for memory usage thresholds can help detect exploitation attempts. Organizations should also consider implementing network segmentation to limit the impact of potential exploitation, as well as maintaining up-to-date backups and recovery procedures. This vulnerability aligns with CWE-401, which specifically addresses improper handling of memory allocation and deallocation, and corresponds to ATT&CK technique T1499.001, which covers network denial of service attacks through resource exhaustion. The fix implemented in kernel version 5.3.12 demonstrates proper memory management practices and error handling protocols that prevent the accumulation of leaked memory resources during USB transfer failures.