CVE-2025-22000 is a vulnerability identified in the Linux kernel's memory management subsystem, specifically within the handling of huge memory pages (folios) in the mm/huge_memory component. The issue arises when a filesystem with a block size larger than the system's page size performs a truncate operation. In such cases, the kernel splits folios into higher order pages (order > 0). However, the code responsible for dropping folios beyond the end-of-file (EOF) does not correctly release all page cache references. The function folio_put_refs(folio, folio_nr_pages(folio)) should be called to release all references, but this is not done properly, resulting in folios not being freed. Consequently, this leads to a memory leak within the kernel's page cache. Over time, this leak can cause increased memory consumption, potentially degrading system performance or causing resource exhaustion. The vulnerability is rooted in incorrect reference counting and memory management logic during truncation operations on filesystems with block sizes exceeding the page size. No known exploits are reported in the wild as of the publication date, and no CVSS score has been assigned yet. The vulnerability affects Linux kernel versions identified by the commit hash c010d47f107f609b9f4d6a103b6dfc53889049e9 or similar. The issue has been publicly disclosed and patched in the Linux kernel source, although patch links are not provided in the data. This vulnerability does not require user interaction or authentication to be triggered, as it is related to kernel-level memory management triggered by filesystem operations.

For European organizations, the impact of CVE-2025-22000 primarily concerns systems running Linux kernels vulnerable to this memory leak, especially those utilizing filesystems with block sizes larger than the system page size and performing frequent truncate operations. The memory leak can lead to gradual degradation of system stability and performance, potentially causing critical services to slow down or crash due to resource exhaustion. This is particularly relevant for servers handling large file operations, such as file servers, database servers, and cloud infrastructure nodes. In environments with high uptime requirements, such as financial institutions, healthcare providers, and critical infrastructure operators, this vulnerability could indirectly affect availability and reliability. Although it does not directly compromise confidentiality or integrity, the resulting denial of service conditions could disrupt business operations and service delivery. Since no known exploits are currently in the wild, the immediate risk is moderate, but the vulnerability should be addressed promptly to prevent future exploitation or operational issues.

To mitigate CVE-2025-22000, organizations should: 1) Apply the latest Linux kernel patches that address this memory leak as soon as they become available from trusted sources or Linux distributions. 2) Identify and monitor systems running affected kernel versions, especially those using filesystems with block sizes larger than the page size (e.g., certain configurations of XFS or ext4). 3) Implement proactive monitoring of kernel memory usage and page cache statistics to detect abnormal memory growth that could indicate the presence of this leak. 4) Where feasible, consider adjusting filesystem block sizes to align with the system page size to reduce the likelihood of triggering the bug. 5) In containerized or virtualized environments, ensure that host kernels are patched promptly, as guest systems rely on host kernel stability. 6) Maintain robust system restart and maintenance schedules to clear leaked memory if patching cannot be immediately applied. 7) Engage with Linux distribution vendors or security mailing lists to receive timely updates and advisories related to this vulnerability.