CVE-2026-98892 in Linux
Summary
by MITRE • 10/23/2026
In the Linux kernel, the following vulnerability has been resolved:
firmware: arm_scmi: Validate BASE_ERROR_EVENT payload size
BASE_ERROR_EVENT carries a variable number of message reports, with the count encoded in error_status. The notification parser used that count without checking whether the received payload contained all reported entries.
Reject truncated payloads before copying the report array.
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Analysis
by VulDB Data Team • 10/23/2026
The Linux kernel's System Control and Management Interface (SCMI) subsystem facilitates communication between a host processor and system management controllers, enabling power management, clock control, and other hardware configuration tasks. A critical vulnerability was identified within the firmware arm_scmi driver, specifically in the handling of BASE_ERROR_EVENT notifications. This event type is designed to carry variable numbers of message reports, with the quantity of these reports encoded directly into an error_status field provided by the remote controller. The core technical flaw lies in the notification parser's failure to validate that the actual payload size received from the hardware matches or exceeds the number of entries indicated by this count. By trusting the external input without verifying the buffer boundaries, the driver proceeds to copy a report array based on an unverified length value.
This lack of bounds checking creates a significant risk for out-of-bounds read vulnerabilities. If a malicious or compromised SCMI controller sends a BASE_ERROR_EVENT with an error_status field indicating more reports than are actually present in the payload buffer, the kernel will attempt to access memory locations beyond the allocated data structure. Depending on the specific implementation details and surrounding memory layout, this can lead to information disclosure where sensitive kernel data is leaked to user space or other processes through malformed event handling paths. In more severe scenarios involving subsequent write operations triggered by such corrupted state, it could potentially facilitate arbitrary code execution or cause a denial of service through system instability caused by accessing invalid memory addresses.
From an industry standards perspective, this vulnerability aligns with CWE-125, which describes Out-of-bounds Read conditions where software reads data past the end, or before the beginning, of the intended buffer. It also relates to CWE-20, Improper Input Validation, as the system failed to correctly validate input that was received from an external source. In terms of attack vectors and techniques, this flaw can be leveraged within the context of ATT&CK technique T1537, which involves Transfer Data to Cloud Account or similar lateral movement scenarios if the SCMI interface is exposed in a virtualized environment where guest OSes interact with hypervisor-managed firmware interfaces. The vulnerability highlights the dangers of trusting hardware-provided metadata without rigorous validation, particularly in low-level system components that operate with high privileges.
To mitigate this risk, it is essential to enforce strict payload size verification before processing any variable-length data structures received from external controllers. Developers must ensure that the length field extracted from protocol messages is compared against the actual buffer size provided by the kernel's memory allocation mechanisms. If the reported count exceeds what can be safely contained within the allocated payload, the operation should be aborted immediately to prevent out-of-bounds access. This defensive programming practice ensures that even if a compromised or faulty controller attempts to exploit this logic error, the system remains protected against memory corruption and data leakage incidents associated with improper input validation in kernel-space drivers.