CVE-2025-39899

CVE-2025-39899 is a Linux kernel vulnerability affecting 32-bit ARM systems with CONFIG_HIGHPTE enabled, specifically within the mm/userfaultfd component. It stems from an incorrect Last-In-First-Out (LIFO) ordering when unmapping PTE pages using kmap_local_page(), leading to a kernel warning. Rated 5.5 MEDIUM (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H), this local vulnerability could result in high availability impact, though it requires local user privileges and low attack complexity. There is no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion surrounding this CVE.