CVE-2026-68400 in Linux
Summary
by MITRE • 08/10/2026
In the Linux kernel, the following vulnerability has been resolved:
firmware: arm_ffa: Fix Endpoint Memory Access Descriptor offset calculation
Use the descriptor's `ep_mem_offset` to calculate the start of the endpoint memory access array and to comply with the FF-A spec instead of defaulting to `sizeof(struct ffa_mem_region)`. This requires moving `ffa_mem_region_additional_setup()` earlier in the setup flow. Also, add sanity checks to ensure the calculated descriptor offsets do not exceed `max_fragsize`.
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Analysis
by VulDB Data Team • 08/10/2026
The vulnerability addressed in this linux kernel patch relates to firmware handling within the arm flexible firmware architecture ffa subsystem where improper memory access descriptor offset calculation could lead to potential security implications. The issue specifically impacts the endpoint memory access descriptor handling mechanism that governs how memory regions are allocated and accessed within the flexible firmware architecture framework. This flaw exists in the arm_ffa module which serves as a critical interface for firmware communication and memory management in arm-based systems.
The technical flaw stems from incorrect offset calculation logic where the system defaults to using sizeof(struct ffa_mem_region) instead of properly utilizing the descriptor's ep_mem_offset field as required by the flexible firmware architecture specification. This deviation from the official specification creates inconsistencies in how memory access arrays are positioned and accessed, potentially leading to memory corruption or unauthorized access patterns. The fix requires reordering the setup sequence to ensure that ffa_mem_region_additional_setup() is called earlier in the initialization process, thereby establishing proper memory layout before subsequent operations attempt to reference these calculated offsets.
The operational impact of this vulnerability extends beyond simple memory management issues as it affects the fundamental integrity of firmware communication channels within arm systems. When endpoint memory access descriptors are improperly calculated, it could enable malicious actors to manipulate memory mappings or potentially escalate privileges by exploiting the incorrect offset calculations. This represents a significant concern in embedded systems and mobile devices where the flexible firmware architecture is commonly employed for secure boot processes and hardware abstraction layers.
The mitigation implemented involves moving the memory region setup function earlier in the initialization flow while adding comprehensive sanity checks to validate that calculated descriptor offsets remain within acceptable bounds defined by max_fragsize. This dual approach ensures both proper ordering of operations and validation of results against established memory constraints, effectively preventing the offset calculation errors that could lead to memory access violations. The fix aligns with security best practices for firmware handling and addresses potential attack vectors identified in the arm flexible firmware architecture specification.
This vulnerability type maps to CWE-129 Input Validation and the ATT&CK technique T1068 Exploitation for Privilege Escalation as it involves improper memory management that could be exploited to gain elevated privileges. The remediation follows standard security practices for firmware architecture implementations, ensuring compliance with established specifications while adding defensive programming measures to prevent similar issues in related components. The patch demonstrates the importance of adhering to specification requirements in firmware development and highlights how seemingly minor offset calculation errors can have significant security implications across embedded systems utilizing flexible firmware architecture frameworks.