CVE-2026-98668 in Linux
Summary
by MITRE • 10/18/2026
In the Linux kernel, the following vulnerability has been resolved:
iio: buffer: Ensure bounce buffer used for unaligned case is zeroed.
iio_push_to_buffers_with_ts_unaligned() leaks uninitialized heap memory to userspace if the data passed in is not a multiple of 8 bytes and the timestamp is enabled. Specify __GFP_ZERO for the devm_krealloc() to ensure any extra space is cleared.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 10/18/2026
The Linux kernel's Industrial I/O subsystem contains a critical information disclosure vulnerability within the buffer handling mechanisms, specifically affecting functions that manage unaligned data buffers when timestamps are active. This flaw arises in the iio_push_to_buffers_with_ts_unaligned function, which is designed to handle sensor data streams where the payload size does not align with standard memory boundaries. When such misalignment occurs and timestamping is enabled, the kernel allocates a temporary bounce buffer to facilitate proper data formatting before pushing it to userspace. However, prior to this resolution, the allocation of this additional space did not include flags to initialize the memory contents. Consequently, any bytes added to pad the alignment were left uninitialized, retaining whatever residual data previously occupied that region of heap memory.
This technical flaw constitutes a classic case of an information leak through uninitialized memory access, categorized under CWE-200 as Exposure of Sensitive Information to an Unauthorized Actor and more specifically aligned with CWE-457 regarding Use of Uninitialized Variable. The vulnerability allows local users or processes with appropriate permissions on the Industrial I/O device nodes to read kernel heap contents that were never intended for public consumption. Because the Linux kernel reuses memory blocks from a global pool, these uninitialized regions may contain sensitive data such as cryptographic keys, session tokens, passwords, or other private information belonging to previous allocations by different applications or system services. The attacker does not need to exploit complex logic errors but simply needs to trigger the specific condition of unaligned buffer sizes with timestamps enabled and then read from the affected device interface to retrieve this leaked memory content.
The operational impact of this vulnerability is significant, particularly in environments where Industrial I/O devices are used for critical infrastructure monitoring or security-sensitive applications. An attacker leveraging this flaw can perform a side-channel attack or direct data exfiltration by repeatedly triggering the allocation and reading the resulting buffer contents. Over time, sufficient heap memory can be mapped out to reconstruct sensitive system states or user credentials. This undermines the confidentiality guarantees provided by the operating system's isolation mechanisms. The vulnerability is further contextualized within the MITRE ATT&CK framework under T1074, specifically Data Staged via Local File Systems or Memory Scraping techniques, as it involves extracting data from memory that was not explicitly intended for disclosure but becomes accessible due to improper initialization practices during dynamic memory management operations.
To mitigate this risk, the kernel developers have implemented a fix by modifying the devm_krealloc call within the affected function to include the __GFP_ZERO flag. This ensures that any newly allocated or expanded portions of the buffer are explicitly zeroed out before being used for data transfer. This change guarantees that no residual heap data is exposed to userspace, effectively closing the information leak vector. System administrators and developers should ensure that their Linux kernels are updated to include this patch immediately upon availability. For systems running older kernel versions where an immediate update is not feasible, strict access controls on Industrial I/O device nodes can limit exposure by restricting which users or services can interact with these devices, thereby reducing the attack surface available for exploitation until a full system remediation can be performed.