CVE-2019-19063 in Linux
Summary
by MITRE
Two memory leaks in the rtl_usb_probe() function in drivers/net/wireless/realtek/rtlwifi/usb.c in the Linux kernel through 5.3.11 allow attackers to cause a denial of service (memory consumption), aka CID-3f9361695113.
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Analysis
by VulDB Data Team • 03/05/2025
The vulnerability identified as CVE-2019-19063 represents a critical memory management flaw within the Linux kernel's wireless networking subsystem, specifically affecting Realtek USB wireless network adapters. This issue resides in the rtl_usb_probe() function located in drivers/net/wireless/realtek/rtlwifi/usb.c, where two distinct memory leaks have been discovered that can be exploited by malicious actors to consume system resources. The vulnerability affects all Linux kernel versions up to and including 5.3.11, making it a widespread concern across numerous production systems and embedded devices that rely on Realtek USB wireless networking hardware.
The technical implementation of this vulnerability stems from improper memory allocation and deallocation practices within the USB wireless driver initialization process. When the rtl_usb_probe() function is invoked during device enumeration, it allocates memory resources to handle USB communication and device configuration but fails to properly release these allocations in certain error handling paths. The dual memory leak condition occurs when the driver encounters specific failure scenarios during probe operations, such as invalid USB descriptors or failed resource allocations, leaving allocated memory blocks unreferenced and permanently unavailable for system use. This memory consumption pattern directly aligns with CWE-401, which catalogs improper resource management vulnerabilities, specifically focusing on memory leaks that can accumulate over time and eventually exhaust available system resources.
From an operational perspective, this vulnerability creates a significant denial of service condition that can severely impact system stability and availability. Attackers can exploit this flaw by repeatedly triggering device probe operations through malicious USB device enumeration or by crafting specific USB device descriptors that force the kernel to enter the problematic code paths. The memory consumption occurs gradually but continuously, with each exploitation event adding to the cumulative memory pressure until the system becomes unresponsive or crashes entirely. This vulnerability particularly affects embedded systems, servers, and IoT devices that rely heavily on USB wireless connectivity, as these platforms typically have limited memory resources and may not have adequate memory management protections in place. The impact extends beyond simple service disruption to potentially compromise system integrity and availability of critical network services.
The mitigation strategies for CVE-2019-19063 primarily involve immediate kernel updates to versions that contain the patched rtl_usb_probe() function implementation. The fix addresses the memory leak conditions by ensuring proper resource cleanup in all error handling paths and implementing robust memory management practices during device initialization. System administrators should prioritize patching affected systems, particularly those running kernel versions 5.3.11 or earlier, as the vulnerability can be exploited remotely through USB device connections. Additional defensive measures include implementing USB device whitelisting policies to restrict unauthorized device enumeration, monitoring system memory consumption for unusual patterns, and deploying intrusion detection systems that can identify suspicious USB device activity. The vulnerability also highlights the importance of proper code review practices for kernel drivers, particularly in resource management and error handling scenarios, aligning with ATT&CK technique T1059.005 for command and scripting interpreter usage in kernel contexts where memory management errors can be amplified through legitimate system operations. Organizations should also consider implementing automated patch management solutions to ensure timely deployment of security fixes and maintain comprehensive inventory of USB device drivers and their associated vulnerabilities.