CVE-2026-98944 in Linux
Summary
by MITRE • 10/23/2026
In the Linux kernel, the following vulnerability has been resolved:
HID: steam: Refactor registration
This refactors and simplifies the registration/unregistration flow. Since we now only perform registration when the client isn't opened anymore, the logic for handling that can be removed, and the rest of the function streamlined.
We also remove the previous assumption that we have a serial number to show we're registered, replacing it with a single purpose boolean.
In a previous refactor the code for unregistering a battery if later registration steps failed was accidentally left out. As a result, a lingering power_supply object could get left over after the steam object was torn down. This is also fixed here.
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Analysis
by VulDB Data Team • 10/23/2026
The Linux kernel HID subsystem contains a driver for Steam controller devices that manages input handling and power supply reporting. A recent update addressed structural issues within this driver by refactoring the registration and unregistration logic to improve code clarity and prevent resource leaks. The core issue stemmed from an incomplete implementation during a prior refactor where error handling paths were not fully updated, leading to potential state inconsistencies when device initialization or teardown processes encountered failures.
The technical flaw involved improper cleanup of power supply objects associated with Steam controllers. Specifically, if registration steps failed after initial setup but before full completion, the code did not properly unregister and destroy the battery power_supply object. This oversight resulted in a lingering kernel object that remained allocated even after the main HID device structure was torn down. Such dangling references can lead to use-after-free vulnerabilities or memory leaks, as subsequent operations might attempt to access resources associated with an already freed or invalid context.
From a security perspective, this vulnerability aligns with CWE-401, which describes missing release of memory after effective usage. In the Linux kernel environment, such errors contribute to resource exhaustion over time and can potentially be exploited for denial-of-service conditions if triggered repeatedly by malicious hardware interaction patterns. Although direct remote code execution is unlikely given the local nature of HID device attachment, maintaining clean state transitions is critical for system stability and integrity.
The mitigation implemented involves restructuring the registration flow so that it only proceeds when necessary and ensuring complete cleanup upon failure or removal. By replacing complex assumptions about serial number presence with a simple boolean flag, the code becomes more robust against edge cases during initialization. Additionally, explicit calls to unregister power supply objects are now included in all exit paths where they were previously omitted. This change ensures that kernel resources are correctly reclaimed regardless of whether registration succeeds or fails midway through the process.
This fix supports adherence to secure coding practices recommended by industry standards for embedded and operating system development. It reduces attack surface complexity by eliminating unnecessary state dependencies and ensuring deterministic behavior during device lifecycle events. System administrators should apply this patch via standard Linux kernel update mechanisms to maintain a hardened environment free from such resource management defects.