CVE-2024-57883 is a vulnerability identified in the Linux kernel's memory management subsystem, specifically within the HugeTLB (Huge Translation Lookaside Buffer) page handling mechanism. The flaw arises from an incorrect reference count management of page tables at the PMD (Page Middle Directory) level. In detail, the kernel function try_get_folio(), which can be called by routines such as split_huge_pages, may unexpectedly increase the folio reference count. The vulnerability manifests because the huge_pmd_unshare() function relies on this reference count to determine if a PMD page table is shared. However, due to the unexpected increment, the check becomes inaccurate, leading to a scenario where the page table is mistakenly considered shared and thus not properly freed. This results in a memory leak of the page table and the HugeTLB pages it maps. The kernel may report a "nonzero mapcount" error and a "Bad page state" bug, indicating corrupted or leaked page structures. The issue can be triggered by kernel components such as damon, offline_page, and page_idle, which interact with page table reference counts. The fix involves introducing an independent PMD page table shared count (pt_share_count) to correctly track sharing status, reusing existing fields used in other architectures for similar purposes. This vulnerability affects Linux kernel versions identified by the commit hash 39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa and is relevant to architectures including x86, arm64, and riscv. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet.

For European organizations, this vulnerability primarily poses a risk to the stability and reliability of Linux-based systems, especially those utilizing HugeTLB pages for performance optimization in memory-intensive applications. The memory leak and improper page table handling can lead to system instability, potential crashes, and degraded performance. While the vulnerability does not directly enable privilege escalation or remote code execution, the resulting kernel instability could be exploited indirectly to cause denial of service (DoS) conditions. This is particularly critical for data centers, cloud service providers, and enterprises relying on Linux servers for critical infrastructure, as unexpected kernel faults can disrupt services and lead to downtime. Systems running workloads with heavy memory management demands, such as databases, virtualization hosts, and high-performance computing clusters, are at higher risk. Given the widespread use of Linux in European governmental, financial, and industrial sectors, the vulnerability could impact a broad range of organizations if unpatched. However, exploitation requires local access and specific kernel interactions, limiting remote attack vectors. The absence of known exploits reduces immediate threat but does not eliminate the risk of future weaponization.

European organizations should prioritize updating their Linux kernels to versions that include the fix for CVE-2024-57883 as soon as patches become available from their Linux distribution vendors. Since the vulnerability involves kernel memory management internals, applying vendor-supplied kernel updates is the most effective mitigation. For environments where immediate patching is not feasible, organizations should monitor kernel logs for signs of "nonzero mapcount" errors or "Bad page state" messages, which may indicate attempts to trigger the flaw. Limiting access to systems to trusted users and processes reduces the risk of exploitation, as local privilege is required to trigger the vulnerability. Additionally, organizations should audit and restrict usage of kernel features or tools known to interact with HugeTLB pages and page table reference counts, such as damon and offline_page, especially in multi-tenant or shared environments. Employing kernel live patching solutions where supported can help mitigate risk without requiring full system reboots. Finally, integrating this vulnerability into vulnerability management and incident response workflows will ensure timely detection and remediation.