CVE-2024-26618 is a vulnerability identified in the Linux kernel specifically affecting the arm64 architecture's SME (Scalable Matrix Extension) memory allocation routine. The issue arises in the sme_alloc() function, which is responsible for allocating storage for SME operations. The vulnerability occurs when sme_alloc() is called with existing storage and no flushing operation is requested. Under these conditions, the function incorrectly allocates new storage without properly freeing or handling the existing storage. This leads to a memory leak and corruption of the internal state related to SME storage management. The root cause is the conflation of checks for flushing and existing storage, which should be handled separately as is done in the similar SVE (Scalable Vector Extension) implementation. The fix involves separating these checks to ensure that existing storage is properly reused or freed, preventing leaks and state corruption. Additionally, callers that need to reallocate storage, for example when changing vector length, must explicitly call sme_free() to release old storage. This vulnerability affects specific Linux kernel versions identified by commit hashes, indicating it is present in certain recent kernel builds prior to the patch. There are no known exploits in the wild at the time of publication, and no CVSS score has been assigned yet. The vulnerability primarily impacts systems running Linux on arm64 platforms that utilize SME features, which are typically found in newer ARM-based processors designed for high-performance computing or specialized workloads.

For European organizations, the impact of CVE-2024-26618 depends largely on their deployment of Linux systems running on arm64 architecture with SME enabled. This vulnerability can cause memory leaks and state corruption in kernel memory management, potentially leading to system instability, crashes, or degraded performance. While it does not directly enable remote code execution or privilege escalation, the corruption could be leveraged in complex attack chains or cause denial of service conditions. Organizations using ARM-based servers, edge devices, or embedded systems in critical infrastructure, telecommunications, or cloud environments may face operational disruptions if unpatched. The memory leak and corruption could also complicate forensic analysis or incident response. Given the increasing adoption of ARM64 servers in Europe for energy-efficient data centers and edge computing, the vulnerability poses a moderate risk to availability and integrity of affected systems. However, the lack of known exploits and the requirement for specific hardware and kernel configurations limit the immediate threat scope. Nonetheless, failure to patch could expose organizations to future exploit attempts or stability issues, impacting service continuity and compliance with operational security standards.

European organizations should take the following specific mitigation steps: 1) Identify all Linux systems running on arm64 architecture, particularly those using kernels with the affected commit hashes or versions. 2) Prioritize patching by applying the latest Linux kernel updates that include the fix for CVE-2024-26618. Since the patch involves kernel-level changes, thorough testing in staging environments is recommended to avoid regressions. 3) For custom or embedded Linux distributions, coordinate with vendors or maintainers to ensure timely integration of the patch. 4) Review and audit any software or drivers that interact with SME features to ensure they correctly manage sme_alloc() and sme_free() calls, preventing improper reallocations. 5) Monitor system logs and kernel messages for signs of memory leaks or corruption related to SME operations. 6) Implement robust backup and recovery procedures to mitigate potential availability impacts from system instability. 7) Engage with hardware vendors to confirm SME support and firmware compatibility with patched kernels. 8) Incorporate this vulnerability into vulnerability management and risk assessment frameworks to track remediation progress and compliance. These targeted actions go beyond generic advice by focusing on architecture-specific identification, patch validation, and operational monitoring tailored to SME usage scenarios.