CVE-2026-63839 in Linux
Summary
by MITRE • 07/19/2026
In the Linux kernel, the following vulnerability has been resolved:
platform/x86: lenovo-wmi-helpers: Fix memory leak in lwmi_dev_evaluate_int()
lwmi_dev_evaluate_int() leaks output.pointer when retval == NULL (found by sashiko.dev [1]).
Fix it by moving `ret_obj = output.pointer' outside of the `if (retval)' block so that it is always freed by the __free cleanup callback.
No functional change intended.
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Analysis
by VulDB Data Team • 07/19/2026
The vulnerability identified in the Linux kernel's platform/x86 subsystem involves a memory leak within the lenovo-wmi-helpers module, specifically in the lwmi_dev_evaluate_int() function. This issue affects systems utilizing Lenovo hardware with WMI (Windows Management Instrumentation) interfaces and represents a classic memory management flaw that can lead to resource exhaustion over time. The vulnerability is categorized under CWE-401 as a failure to release memory resources, which directly impacts system stability and performance. The flaw manifests when the function processes WMI method calls and fails to properly handle memory cleanup in error conditions.
The technical implementation of this vulnerability stems from improper control flow management within the lwmi_dev_evaluate_int() function where the output.pointer assignment occurs inside a conditional block that only executes when retval is non-null. When retval equals NULL, indicating an error condition or failed WMI evaluation, the output.pointer value remains uninitialized and consequently never gets freed through the established __free cleanup callback mechanism. This creates a memory leak scenario where allocated memory persists in system RAM without proper deallocation, potentially leading to gradual memory consumption that could impact overall system performance and stability.
The operational impact of this vulnerability extends beyond simple memory wastage, as it represents a potential vector for resource exhaustion attacks particularly in embedded systems or environments where memory resources are constrained. Attackers could theoretically exploit this weakness by repeatedly triggering WMI method calls that result in NULL return values, causing progressive memory fragmentation and eventual system instability. The vulnerability affects Lenovo devices that utilize the WMI interface for hardware management and configuration, making it relevant to a significant portion of enterprise and consumer laptops. From an ATT&CK framework perspective, this represents a resource exhaustion technique that could be leveraged as part of broader attack chains targeting system availability.
The fix implemented addresses this issue by reorganizing the code structure to ensure that ret_obj = output.pointer assignment occurs outside of the conditional block that checks retval status. This modification guarantees that regardless of whether retval is NULL or contains a valid return value, the memory management cleanup callback will always have access to the pointer value for proper deallocation. The solution maintains complete functional equivalence while eliminating the memory leak through careful control flow restructuring. This approach aligns with standard secure coding practices recommended by both CWE guidelines and industry security frameworks, ensuring that all allocated resources are properly released even in error conditions. The remediation effectively closes the vulnerability without introducing any behavioral changes to the function's normal operation or user experience.