CVE-2025-38667 in Linux
Summary
by MITRE • 08/22/2025
In the Linux kernel, the following vulnerability has been resolved:
iio: fix potential out-of-bound write
The buffer is set to 20 characters. If a caller write more characters, count is truncated to the max available space in "simple_write_to_buffer". To protect from OoB access, check that the input size fit into buffer and add a zero terminator after copy to the end of the copied data.
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Analysis
by VulDB Data Team • 02/14/2026
This vulnerability exists within the Linux kernel's industrial I/O subsystem where improper bounds checking can lead to out-of-bounds memory write conditions. The issue specifically affects the buffer management functionality that handles data transfers between user space and kernel space. When data is written to an I/O buffer that has been allocated with a fixed size of 20 characters, the system fails to validate whether the incoming data exceeds this boundary limit. The simple_write_to_buffer function truncates the count parameter to fit within available space but does not perform adequate validation to prevent buffer overflow conditions. This flaw represents a classic buffer overflow vulnerability that can be exploited to overwrite adjacent memory locations, potentially leading to arbitrary code execution or system instability.
The technical implementation of this vulnerability stems from inadequate input validation within the kernel's I/O buffer handling mechanisms. The system allocates a 20-character buffer for data transfer operations but does not properly verify that the size of incoming data fits within these boundaries before performing the copy operation. While the code does implement truncation logic, it lacks proper bounds checking to ensure that the input data size does not exceed the allocated buffer capacity. The absence of a zero terminator after copying data to the end of the buffer creates additional risk for memory corruption and can lead to unpredictable behavior when the buffer content is later processed or interpreted by other kernel components. This type of vulnerability is categorized under CWE-121 as a stack-based buffer overflow, though in kernel contexts it can manifest as heap-based or memory corruption issues.
The operational impact of this vulnerability extends across all systems utilizing the Linux kernel's industrial I/O subsystem where user-space applications interact with kernel-level I/O buffers. Attackers could potentially exploit this condition by crafting malicious input data that exceeds the 20-character limit, causing the kernel to write beyond allocated memory boundaries. This could result in system crashes, denial of service conditions, or more severe exploitation leading to privilege escalation. The vulnerability is particularly concerning in embedded systems, industrial control environments, and IoT devices that rely heavily on kernel I/O operations for sensor data collection and device communication. The attack surface is broad given the widespread use of Linux kernel I/O subsystems in various computing environments from servers to specialized hardware platforms.
Mitigation strategies for this vulnerability should focus on implementing robust input validation and bounds checking within the kernel's buffer management code. The fix requires adding explicit checks to verify that input data sizes do not exceed the allocated buffer capacity before any copy operations occur. Additionally, ensuring proper null termination of copied data is essential to prevent memory corruption issues that could arise from unterminated strings. System administrators should prioritize updating to kernel versions that contain the patched implementation, which typically includes enhanced validation routines and proper buffer boundary checks. The mitigation approach aligns with ATT&CK technique T1068 which involves exploiting vulnerabilities in kernel space, making it critical to maintain up-to-date kernel versions and implement proper security controls. Organizations should also consider implementing kernel module hardening techniques and monitoring for suspicious I/O operations that might indicate exploitation attempts. Regular security audits of kernel code and input validation routines can help identify similar vulnerabilities in other subsystems and maintain overall system security posture.