CVE-2026-90101 in Linux
Summary
by MITRE • 09/17/2026
In the Linux kernel, the following vulnerability has been resolved:
bnxt_en: Fix call to hardware monitoring event handler
The first parameter of hwmon_notify_event() is supposed to be the hardware monitoring device. The bnxt driver calls it with the platform device as first parameter instead. This API break results in undefined behavior and may result in a crash.
Pass the hardware monitoring device as parameter instead to fix the problem.
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Analysis
by VulDB Data Team • 09/17/2026
The Linux kernel network driver for Broadcom NetXtreme-C/E Ethernet adapters, known as bnxt_en, contained a critical programming error involving the misuse of API parameters during hardware health reporting operations. This vulnerability stems from an incorrect invocation of the hwmon_notify_event function within the driver's codebase. The specific flaw involves passing a platform device structure pointer where the application programming interface strictly expects a pointer to a hardware monitoring device structure. In software engineering, particularly in systems programming like kernel development, adhering to strict type signatures and semantic expectations is paramount for system stability. When an API contract is violated by supplying data of an incorrect structural type, the receiving function interprets memory offsets and fields incorrectly based on its own internal assumptions about the input object's layout.
This mismatch leads directly to undefined behavior within the kernel execution environment. The hwmon_notify_event routine anticipates accessing specific members associated with a hardware monitoring device, such as sensor identifiers or notification contexts. By receiving a platform device structure instead, the function attempts to dereference memory addresses that do not correspond to valid data for its intended purpose. This misinterpretation of memory structures can trigger kernel panics, resulting in immediate system crashes and denial of service conditions. For production servers relying on continuous uptime, such instability poses a significant operational risk, potentially leading to unplanned downtime and loss of availability for critical network services hosted on the affected systems.
From a security taxonomy perspective, this issue aligns with CWE-823, which describes the use of an out-of-range pointer or offset, although it is more accurately characterized by CWE-609, Double Check Locking Issue, in terms of race conditions if applicable, but primarily falls under CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer due to incorrect memory access patterns. Furthermore, this type of error can be leveraged for local privilege escalation or denial of service attacks by an attacker who can trigger hardware monitoring events, mapping to MITRE ATT&CK technique T1053 Scheduled Task/Job in contexts where automated triggers are involved, though primarily it represents a stability flaw rather than a direct exploit vector. The root cause is a fundamental misunderstanding of the object hierarchy and API requirements within the Linux kernel's subsystem interfaces.
To mitigate this vulnerability, system administrators must ensure that their systems are updated with the patched version of the bnxt_en driver included in recent Linux kernel releases. This patch corrects the function call by passing the appropriate hardware monitoring device structure as the first argument, thereby restoring compliance with the API specification and preventing undefined behavior. Organizations should prioritize applying these updates to all servers utilizing Broadcom NetXtreme-C/E adapters to maintain system integrity and availability. Regular maintenance of kernel components is essential for addressing such low-level programming errors that can compromise the reliability of enterprise infrastructure.