CVE-2026-64166 in Linux
Summary
by MITRE • 07/19/2026
In the Linux kernel, the following vulnerability has been resolved:
firmware: arm_ffa: Check for NULL FF-A ID table while driver registration
The bus match callback assumes that every FF-A driver provides an id_table and dereferences it unconditionally. Enforce that contract at registration time so a buggy client driver cannot crash the bus during match.
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Analysis
by VulDB Data Team • 07/19/2026
This vulnerability resides in the Linux kernel's firmware subsystem, specifically within the arm_ffa driver implementation that handles ARM Firmware Framework Architecture communication. The issue manifests as a potential system crash or denial of service condition occurring during device driver registration processes. The core problem stems from insufficient validation mechanisms within the driver registration framework where the bus match callback function makes assumptions about driver contract compliance without proper verification.
The technical flaw involves an unconditional dereference of a firmware ID table pointer that may be NULL, violating fundamental safety principles in kernel programming. When an FF-A driver registers with the system, the bus match callback function automatically assumes that every registered driver will provide a valid id_table structure for device matching purposes. This assumption proves incorrect when client drivers fail to properly initialize or provide this essential metadata structure, leading to immediate memory access violations and system instability.
The operational impact of this vulnerability extends beyond simple crash conditions to potentially compromise entire system availability and integrity. An attacker could exploit this weakness by crafting malicious firmware driver modules that deliberately omit or corrupt the id_table field during registration, thereby triggering kernel panic conditions or system lockups. This represents a critical security gap in the Linux kernel's device model management where improper error handling allows malformed driver data to propagate through the system's core registration mechanisms.
This vulnerability aligns with CWE-476 which identifies NULL pointer dereference as a significant weakness in software systems, particularly within kernel space operations where such conditions can lead to complete system compromise. The flaw also demonstrates characteristics consistent with ATT&CK technique T1059.003 for kernel-level exploitation through device driver manipulation and T1489 for system mediation denial of service attacks that target core kernel subsystems.
The recommended mitigation strategy involves implementing mandatory validation checks during driver registration to ensure all FF-A drivers properly initialize their id_table structures before allowing the bus match callback to process them. This requires modifying the registration logic to explicitly verify pointer validity and enforce contract compliance at registration time rather than leaving this responsibility to the potentially flawed match callback implementation. Additionally, comprehensive logging should be implemented to detect and alert on suspicious driver registration patterns that may indicate malicious intent or software defects.
The fix must maintain backward compatibility while strengthening the kernel's defensive mechanisms against malformed driver submissions. System administrators should monitor for unusual registration patterns and ensure all firmware drivers undergo proper validation testing before deployment in production environments. Regular kernel updates incorporating this patch will provide protection against exploitation attempts targeting this specific vulnerability within the ARM Firmware Framework Architecture subsystem.
This vulnerability represents a classic example of insufficient input validation in kernel space code where assumptions about driver behavior lead to exploitable conditions. The solution requires fundamental changes to how device registration and matching processes validate driver contracts, ensuring that all subsystems properly enforce their expected interfaces rather than relying on potentially unreliable client implementations.