CVE-2026-80624 in Linux
Summary
by MITRE • 08/28/2026
In the Linux kernel, the following vulnerability has been resolved:
mfd: cs42l43: Sanity check firmware size
Currently the code checks if a firmware was received, however it does not verify that the firmware size is larger than the firmware header. As the firmware pointer is dereferenced as a pointer to the header structure this could lead to an out of bounds memory access. Add the missing check.
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Analysis
by VulDB Data Team • 08/28/2026
The Linux kernel driver for the Cirrus Logic CS42L43 multi-function device contains a critical input validation flaw within its firmware loading routine, specifically identified in the mfd subsystem. This vulnerability arises from an insufficient boundary check during the initialization phase where external firmware images are processed by the operating system. The existing implementation correctly verifies that a firmware blob has been successfully received and allocated in memory, ensuring that the pointer is not null. However, it fails to validate whether the size of this incoming data stream exceeds the minimum required length defined by the internal header structure used to interpret the configuration parameters. This oversight creates a scenario where truncated or malformed firmware files can be accepted without triggering an error condition, allowing execution to proceed with incomplete data structures.
From a technical perspective, the core issue is rooted in improper input validation leading to out-of-bounds memory access. The driver code dereferences the received firmware pointer as if it were pointing to a specific header structure containing essential configuration metadata. When the actual size of the provided firmware image is smaller than the sizeof this expected header structure, any subsequent read operation targeting fields within that header will attempt to access memory locations beyond the allocated buffer boundaries. This constitutes an out-of-bounds read vulnerability, which falls under CWE-125 in the Common Weakness Enumeration taxonomy. Such memory violations can lead to unpredictable system behavior, including kernel panics due to page faults or segmentation violations when accessing unmapped pages, thereby causing a denial of service condition for the local system.
The operational impact of this flaw is significant depending on how the firmware loading mechanism is triggered in production environments. If the CS42L43 driver supports hot-plug scenarios or allows userspace applications to trigger firmware updates via sysfs interfaces without strict privilege restrictions, an attacker with limited access could potentially exploit this condition by supplying a crafted, undersized binary file. While primarily resulting in stability issues such as kernel crashes rather than immediate arbitrary code execution due to the read-only nature of most header accesses, out-of-bounds reads can sometimes leak sensitive memory contents if the accessed bytes contain confidential data from adjacent allocations. Furthermore, repeated exploitation attempts could destabilize system resources and degrade overall performance through frequent fault handling overheads. This type of vulnerability aligns with ATT&CK technique T1059, specifically involving command or script interpretation within local contexts where drivers are manipulated to alter hardware state.
To mitigate this risk, the primary remediation involves implementing a rigorous sanity check that compares the length of the received firmware image against the size of the expected header structure before any dereferencing occurs. Developers must ensure that the validation logic explicitly rejects payloads shorter than the minimum required threshold, returning an appropriate error code such as -EINVAL to indicate invalid input parameters. Additionally, it is advisable to audit other similar drivers in the multi-function device subsystem for analogous patterns where firmware or configuration blobs are processed without comprehensive size verification. Regular static analysis and fuzzing of driver interfaces can help identify these gaps early in the development lifecycle. System administrators should apply kernel updates that include this patch promptly to restore secure operation boundaries, ensuring that only well-formed and sufficiently sized firmware images are accepted by the hardware abstraction layer.