CVE-2024-26795 is a vulnerability identified in the Linux kernel specifically affecting the RISC-V architecture's sparse memory management subsystem, particularly the vmemmap (virtual memory map) handling. The issue involves an out-of-bounds memory access due to incorrect offsetting of the vmemmap structure. The vmemmap is a critical kernel data structure that maps physical memory pages to kernel virtual addresses, enabling the kernel to manage physical memory efficiently. In this vulnerability, the first page of the vmemmap was not correctly aligned with the first page of physical memory, causing the pfn_to_page() and page_to_pfn() conversion macros to potentially produce invalid addresses. This misalignment could lead to out-of-bounds reads or writes during memory management operations, potentially causing kernel crashes, memory corruption, or undefined behavior. The fix involves adjusting the offset of the vmemmap so that its first page aligns correctly with the physical memory's first page, ensuring that all address conversions respect the physical memory boundaries. This correction guarantees that the conversion macros produce valid SV39/48/57 virtual addresses for all valid DRAM_BASE values within physical memory limits. The vulnerability is specific to the RISC-V architecture implementation in the Linux kernel and was addressed in a patch released in early 2024. There are no known exploits in the wild at this time, and the vulnerability requires kernel-level access or conditions to trigger, as it involves low-level memory management internals. No CVSS score has been assigned yet, and the vulnerability does not appear to be remotely exploitable without prior access or privilege escalation.

For European organizations, the impact of CVE-2024-26795 depends largely on their use of Linux systems running on RISC-V architecture hardware. While RISC-V adoption is growing, it remains less common compared to x86 and ARM architectures in enterprise environments. However, organizations involved in research, embedded systems, IoT, or specialized computing that utilize RISC-V Linux kernels could be affected. The vulnerability could lead to system instability, kernel panics, or potential privilege escalation if exploited in conjunction with other vulnerabilities. This could disrupt critical services, cause data loss, or enable attackers to gain elevated privileges on affected systems. Given the kernel-level nature of the flaw, successful exploitation could compromise the confidentiality, integrity, and availability of systems. Although no exploits are currently known, the vulnerability represents a risk for organizations deploying RISC-V Linux in production or development environments. European entities in sectors such as telecommunications, automotive, industrial control, and academia—where RISC-V is gaining traction—should be particularly vigilant. The overall impact is moderate at present but could increase as RISC-V adoption expands.

European organizations should take the following specific mitigation steps: 1) Identify and inventory all Linux systems running on RISC-V architecture within their environment, including embedded and IoT devices. 2) Apply the official Linux kernel patches that address CVE-2024-26795 as soon as they become available from trusted sources or Linux distributions. 3) For systems where immediate patching is not feasible, consider isolating RISC-V Linux hosts from critical networks to reduce attack surface. 4) Monitor kernel logs and system behavior for signs of memory corruption or instability that could indicate exploitation attempts. 5) Implement strict access controls to limit kernel-level access and reduce the risk of privilege escalation. 6) Engage with hardware and software vendors to ensure timely updates and support for RISC-V platforms. 7) Incorporate this vulnerability into vulnerability management and incident response plans, emphasizing the unique aspects of RISC-V Linux environments. These targeted actions go beyond generic advice by focusing on architecture-specific identification, patch management, and operational controls.