CVE-2026-74604 in Linux
Summary
by MITRE • 08/22/2026
In the Linux kernel, the following vulnerability has been resolved:
Revert "thermal/drivers/hwmon: Cleanup coding style a bit"
Revert commit 030a48b0f6ce ("thermal/drivers/hwmon: Cleanup coding style a bit") that introduced a use-after-free into the error path of thermal_add_hwmon_sysfs() by removing a valid check from it.
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Analysis
by VulDB Data Team • 08/22/2026
The Linux kernel has addressed a critical memory safety issue within its hardware monitoring subsystem, specifically in the thermal management driver code responsible for exposing sensor data to user space via sysfs. The vulnerability was introduced through an earlier commit that attempted to streamline coding style and remove redundant checks from the thermal_add_hwmon_sysfs function. This optimization inadvertently removed a necessary validation step during error handling paths, leading directly to a use-after-free condition. Use-after-free vulnerabilities occur when software continues to use memory after it has been freed, which can lead to unpredictable behavior, system crashes, or potentially arbitrary code execution if an attacker can control the contents of the reallocated memory region.
The technical root cause lies in the error path of thermal_add_hwmon_sysfs, a function responsible for creating sysfs entries that allow users and applications to read temperature data from hardware monitoring chips. When this function encounters an error during initialization or registration, it must ensure proper cleanup of allocated resources before returning control to the caller. The reverted commit had stripped away a check that was critical for ensuring that pointers were not accessed after being deallocated in these failure scenarios. By removing this safeguard, the kernel allowed references to freed memory structures to persist, creating a window where subsequent operations could interact with invalid memory addresses. This type of flaw is particularly dangerous because it can be triggered by local users who have access to thermal sensors or through specific hardware configurations that induce error conditions during sysfs registration.
From an operational impact perspective, this vulnerability poses significant risks to system stability and security integrity. A successful exploitation could result in a kernel panic, causing a denial of service for the entire host machine. More critically, if the freed memory is reallocated by another process or subsystem with attacker-controlled data, it may lead to privilege escalation or remote code execution depending on the context in which the dangling pointer is dereferenced. Although this vulnerability resides within thermal drivers, which are typically accessed locally, the potential for exploitation remains high due to the privileged nature of kernel-space operations. The presence of such flaws undermines trust in the operating system's ability to isolate processes and manage resources safely, especially in environments where multiple untrusted workloads share a single physical host.
To mitigate this risk, users should apply the latest available kernel updates that include the revert commit 030a48b0f6ce. System administrators must ensure their systems are patched promptly, particularly those running versions of Linux affected by the flawed coding style cleanup in thermal drivers. For organizations managing large fleets of servers or embedded devices relying on hardware monitoring features, automated patch management tools should be configured to detect and deploy this specific fix without delay. Additionally, developers working with kernel subsystems involving sysfs interfaces must adhere strictly to defensive programming practices, ensuring that all error paths include comprehensive resource cleanup checks. This incident highlights the importance of rigorous code review processes when modifying low-level driver logic, as even minor stylistic changes can introduce severe security vulnerabilities if they compromise memory safety guarantees.
This vulnerability aligns with Common Weakness Enumeration CWE-416, which describes use-after-free conditions resulting from improper handling of freed pointers. It also relates to ATT&CK technique T1059, specifically within the context of local execution and potential privilege escalation via kernel exploitation vectors. Security teams should monitor for indicators of compromise related to abnormal thermal driver behavior or unexpected system crashes that may signal attempted exploitation of this flaw. Continuous integration pipelines involving kernel code changes must include static analysis tools capable of detecting memory management errors in error paths, ensuring that future patches do not reintroduce similar weaknesses through well-intentioned but unsafe refactoring efforts.