{"id":"CVE-2025-21851","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix softlockup in arena_map_free on 64k page kernel\n\nOn an aarch64 kernel with CONFIG_PAGE_SIZE_64KB=y,\narena_htab tests cause a segmentation fault and soft lockup…","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix softlockup in arena_map_free on 64k page kernel\n\nOn an aarch64 kernel with CONFIG_PAGE_SIZE_64KB=y,\narena_htab tests cause a segmentation fault and soft lockup…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cwe":["CWE-667","CWE-667"],"vendor":"linux","product":"linux_kernel","affected":["linux_kernel >= 6.9, < 6.12.17","linux_kernel >= 6.13, < 6.13.5","linux_kernel = 6.9","linux_kernel = 6.14"],"patched":["linux_kernel 6.13.5"],"published":"2025-03-12","updated":"2026-07-30","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2025-21851","references":[{"url":"https://git.kernel.org/stable/c/517e8a7835e8cfb398a0aeb0133de50e31cae32b","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/787d556a3de447e70964a4bdeba9196f62a62b1e","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/c1f3f3892d4526f18aaeffdb6068ce861e793ee3","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"tags":["nvd"],"epss":0.00173,"epssPercentile":0.05958,"ingestedAt":"2026-07-30T06:53:10.540Z","slug":"CVE-2025-21851","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix softlockup in arena_map_free on 64k page kernel\n\nOn an aarch64 kernel with CONFIG_PAGE_SIZE_64KB=y,\narena_htab tests cause a segmentation fault and soft lockup.\nThe same failure is not observed with 4k pages on aarch64.\n\nIt turns out arena_map_free() is calling\napply_to_existing_page_range() with the address returned by\nbpf_arena_get_kern_vm_start().  If this address is not page-aligned\nthe code ends up calling apply_to_pte_range() with that unaligned\naddress causing soft lockup.\n\nFix it by round up GUARD_SZ to PAGE_SIZE << 1 so that the\ndivision by 2 in bpf_arena_get_kern_vm_start() returns\na page-aligned value.\n\n## Affected\n\n- `linux_kernel >= 6.9, < 6.12.17`\n- `linux_kernel >= 6.13, < 6.13.5`\n- `linux_kernel = 6.9`\n- `linux_kernel = 6.14`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 6.13.5`","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}