CVE-2026-98658 in Linux
Summary
by MITRE • 10/18/2026
In the Linux kernel, the following vulnerability has been resolved:
iio: proximity: aw96103: validate firmware data length
The firmware parser reads a length from the binary header and then uses it to walk six-byte register/value entries. A truncated firmware image can make the parser read beyond the copied firmware buffer. A value smaller than the four-byte count field also underflows, producing a very large length.
Read the little-endian field with get_unaligned_le32(), as previously proposed by David Lechner. Validate the header size, reject an underflowed length, ensure the resulting payload is contained in the firmware image, and require it to contain whole register/value entries.
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Analysis
by VulDB Data Team • 10/18/2026
The Linux kernel driver for the ams aw96103 proximity sensor contains a critical input validation flaw within its firmware parsing logic that can lead to out-of-bounds memory access and potential system instability or compromise. This vulnerability arises from insufficient checks on data structures extracted directly from external binary files, specifically when loading device-specific configuration data into kernel space. The driver is responsible for interpreting a proprietary firmware format consisting of register-value pairs used to configure the sensor hardware during initialization. Without rigorous validation of these inputs, maliciously crafted or corrupted firmware images can exploit parsing routines that assume well-formed input, leading to severe memory safety violations.
The technical root cause lies in how the parser handles length fields and buffer boundaries within the firmware header. The code reads a count field from the binary image using standard little-endian conversion functions but fails to adequately validate its magnitude before performing arithmetic operations or array indexing. Specifically, if the value stored in this four-byte count field is smaller than the size of the structure it represents, an integer underflow occurs during subsequent calculations involving entry sizes. This results in a drastically inflated length value that does not reflect the actual data available. Furthermore, even when the length appears valid, there was no check to ensure that the calculated end offset remains within the bounds of the allocated firmware buffer. Consequently, accessing six-byte register-value entries based on this corrupted length causes the parser to read memory beyond the intended buffer boundary.
This out-of-bounds read constitutes a significant security risk as it allows for information disclosure by leaking kernel memory contents to user space or triggering undefined behavior that may crash the system. In worst-case scenarios involving specific execution contexts, such memory corruption can be leveraged for privilege escalation if combined with other vulnerabilities, although primarily this flaw impacts availability and data integrity. The lack of alignment checks also means that improperly aligned reads could occur on architectures requiring strict alignment, potentially causing hardware exceptions or further instability. These issues highlight the dangers of trusting external binary inputs without comprehensive sanitization in kernel drivers.
To mitigate these risks, the vulnerability was addressed by implementing robust input validation mechanisms within the firmware parser. The fix introduces explicit checks to verify that the header size is sufficient and that the length field does not result in an underflow when processed against entry sizes. Additionally, boundary checks were added to ensure that the entire payload described by the length fits entirely within the copied firmware buffer before any parsing begins. By requiring that the data contains whole register-value entries and rejecting truncated or malformed images early in the process, the driver prevents out-of-bounds access attempts. This approach aligns with secure coding practices for kernel modules handling external configuration files.
From a classification perspective, this vulnerability maps to CWE-125 Out-of-bounds Read, as it involves accessing memory locations beyond allocated buffers due to improper length validation. It also relates to CWE-682 Incorrect Calculation, stemming from the integer underflow that produces an excessively large loop count or access range. In terms of attack vectors and techniques, this flaw is relevant to ATT&CK technique T1059 Command and Scripting Interpreter if considered in the context of loading malicious scripts, but more accurately it falls under data injection patterns where untrusted input leads to memory corruption. Defense-in-depth strategies should include strict validation of all external binary inputs at their entry points into privileged code paths, ensuring that size fields are checked for reasonableness before being used for memory allocation or iteration bounds.