CVE-2026-43143 Overview
CVE-2026-43143 is a concurrency vulnerability in the Linux kernel's Multi-Function Device (MFD) core subsystem. The flaw exists in code that manipulates the global mfd_of_node_list without mutual exclusion. Concurrent access to this list can lead to inconsistent state and potential kernel crashes. The upstream fix introduces a mutex around all access and modification points for mfd_of_node_list.
Critical Impact
Unsynchronized list manipulation in drivers/mfd/mfd-core.c can corrupt kernel data structures and trigger denial-of-service conditions on affected systems.
Affected Products
- Linux kernel mainline branches prior to the patch commits referenced in the kernel.org stable tree
- Linux kernel stable branches receiving backports via commits 20117c92, 45341856, 9b02e3fe, db131ef9, dcfa679b, and e2e7c275
- Distributions shipping vulnerable kernel versions that include the MFD core subsystem
Discovery Timeline
- 2026-05-06 - CVE-2026-43143 published to NVD
- 2026-05-06 - Last updated in NVD database
Technical Details for CVE-2026-43143
Vulnerability Analysis
The Linux kernel MFD (Multi-Function Device) core subsystem maintains a global linked list named mfd_of_node_list. This list tracks device tree node associations for MFD child devices. The original implementation modified and traversed this list without holding a lock.
Kernel linked-list manipulation is not safe under concurrent execution. When multiple kernel threads, probe paths, or driver registrations interact with mfd_of_node_list simultaneously, list pointers can become inconsistent. The result is data corruption in kernel memory and possible kernel oops or panic.
The patch resolves the issue by adding a mutex that serializes all read and write access to mfd_of_node_list. This ensures atomicity around list operations such as insertion, removal, and traversal. The fix is an instance of a classic race condition [CWE-362] involving shared kernel data.
Root Cause
The root cause is missing synchronization on a shared kernel data structure. The MFD core code manipulated mfd_of_node_list from multiple call sites without holding any lock. Kernel linked lists require explicit locking by callers, since the list primitives themselves are not thread-safe.
Attack Vector
Triggering the race requires concurrent kernel paths that operate on MFD device tree nodes. The exploitation surface is local and depends on driver probe timing, hot-plug events, or module load and unload sequences. No remote exploitation vector is documented. The most likely outcome is a kernel crash leading to denial of service rather than privilege escalation.
The vulnerability is described in prose rather than code because no verified public exploit code exists. The fix details are available in the upstream commits on the kernel.org stable tree, including Kernel Commit 20117c92 and Kernel Commit e2e7c275.
Detection Methods for CVE-2026-43143
Indicators of Compromise
- Unexpected kernel oops messages referencing mfd_of_node_list, mfd-core.c, or list traversal functions such as list_add, list_del, or list_for_each_entry
- Kernel panics during driver probe, module load, or device tree node enumeration on systems running unpatched MFD core code
- Lockdep or KASAN warnings flagging concurrent access to MFD data structures in test environments
Detection Strategies
- Inventory running kernel versions across Linux endpoints and servers and compare against the patched stable releases referenced in the kernel.org commits
- Enable kernel diagnostics such as lockdep, KASAN, and KCSAN in test or staging builds to surface race conditions in MFD code paths
- Monitor /var/log/kern.log, journalctl -k, and crash dumps for repeated faults inside MFD subsystem symbols
Monitoring Recommendations
- Forward kernel logs to a centralized logging or SIEM platform to track unplanned reboots and kernel faults across the fleet
- Alert on repeated kernel panics on the same host, which can indicate a triggerable race condition rather than transient hardware issues
- Track package and kernel update compliance using configuration management tooling to confirm patched kernels are deployed
How to Mitigate CVE-2026-43143
Immediate Actions Required
- Update affected Linux systems to kernel versions that include the upstream fix commits referenced in the NVD entry
- Prioritize patching on systems that load multiple MFD-backed drivers, such as embedded platforms, ARM SoCs, and devices with rich power-management ICs
- Validate kernel build configurations to confirm the patched MFD core source is compiled into deployed images
Patch Information
The upstream fix adds a mutex around every access to mfd_of_node_list in the MFD core. Patch sets are available across multiple stable branches via the kernel.org commits: Kernel Commit 20117c92, Kernel Commit 45341856, Kernel Commit 9b02e3fe, Kernel Commit db131ef9, Kernel Commit dcfa679b, and Kernel Commit e2e7c275. Apply the vendor-supplied kernel update from your Linux distribution once available.
Workarounds
- No documented workaround replaces the upstream patch; backporting the mutex change is the recommended remediation for custom kernels
- Reduce concurrent driver probe pressure on impacted systems by limiting dynamic module loading until a patched kernel is deployed
- For embedded and IoT fleets, schedule firmware updates that incorporate the patched kernel through your standard release process
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
