{"id":"CVE-2026-68172","state":"PUBLISHED","title":"arm64: make huge_ptep_get handled unaligned addresses","description":"In the Linux kernel, the following vulnerability has been resolved:\n\narm64: make huge_ptep_get handled unaligned addresses\n\nhuge_ptep_get() can be handed a virtual address pointing to the middle\nof a contpmd/contpte mapped hugetlb folio (examples of callers are\npagemap_hugetlb_range, page_mapped_in_vma).\n\nThe arm64 helper rewalks the pgtables in find_num_contig to answer\nwhether the huge pte we have maps a contpmd or a contpte hugetlb folio,\nand returns CONT_PMDS or CONT_PTES, so that it can collect a/d bits over\nthe contiguous ptes. We can falsely return CONT_PTES instead of\nCONT_PMDS if the addr is not aligned. On systems where CONT_PTES !=\nCONT_PMDS (meaning page size is 16K), we could collect excess A/D bit\nstate, meaning extra work for the kernel. Even worse, we may iterate\nbeyond the PTE table and dereference a garbage ptep pointer to access\nphysical memory we don't own. Since the ptep pointer is a linear map\naddress, we may run off the end of the linear map or into a hole,\ndereference a VA not mapped into the kernel pgtables and cause kernel\npanic.\n\nFix this by aligning the pmdp pointer down to a contpmd base before\nchecking equality with the passed huge pte pointer, to correctly answer\nwhether the huge pte is the base of a contpmd block.","publishedAt":"2026-08-10T11:59:41.893Z","updatedAt":"2026-08-17T05:00:12.926Z","severity":{"score":7.1,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"29cb80519689706387bde47000dbb2ed91143063","status":"affected","lessThan":"9cd4b1a52eff330798d668c1775f8bc450776280","versionType":"git"},{"version":"29cb80519689706387bde47000dbb2ed91143063","status":"affected","lessThan":"f3530aec26563f4d483ff31402392961362e9bc6","versionType":"git"},{"version":"29cb80519689706387bde47000dbb2ed91143063","status":"affected","lessThan":"f73a8edc2ccc6ec72c37d5c578e7592d2e1f9922","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/arm64/mm/hugetlbpage.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.16","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.16","versionType":"semver"},{"version":"6.18.42","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.6","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/arm64/mm/hugetlbpage.c"]}],"references":["https://git.kernel.org/stable/c/9cd4b1a52eff330798d668c1775f8bc450776280","https://git.kernel.org/stable/c/f3530aec26563f4d483ff31402392961362e9bc6","https://git.kernel.org/stable/c/f73a8edc2ccc6ec72c37d5c578e7592d2e1f9922"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:49.727Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/68xxx/CVE-2026-68172.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-68172","state":"PUBLISHED","datePublished":"2026-08-10T11:59:41.893Z","dateUpdated":"2026-08-17T05:00:12.926Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-30T09:28:09.372Z"},"containers":{"cna":{"title":"arm64: make huge_ptep_get handled unaligned addresses","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\narm64: make huge_ptep_get handled unaligned addresses\n\nhuge_ptep_get() can be handed a virtual address pointing to the middle\nof a contpmd/contpte mapped hugetlb folio (examples of callers are\npagemap_hugetlb_range, page_mapped_in_vma).\n\nThe arm64 helper rewalks the pgtables in find_num_contig to answer\nwhether the huge pte we have maps a contpmd or a contpte hugetlb folio,\nand returns CONT_PMDS or CONT_PTES, so that it can collect a/d bits over\nthe contiguous ptes. We can falsely return CONT_PTES instead of\nCONT_PMDS if the addr is not aligned. On systems where CONT_PTES !=\nCONT_PMDS (meaning page size is 16K), we could collect excess A/D bit\nstate, meaning extra work for the kernel. Even worse, we may iterate\nbeyond the PTE table and dereference a garbage ptep pointer to access\nphysical memory we don't own. Since the ptep pointer is a linear map\naddress, we may run off the end of the linear map or into a hole,\ndereference a VA not mapped into the kernel pgtables and cause kernel\npanic.\n\nFix this by aligning the pmdp pointer down to a contpmd base before\nchecking equality with the passed huge pte pointer, to correctly answer\nwhether the huge pte is the base of a contpmd block."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"29cb80519689706387bde47000dbb2ed91143063","status":"affected","lessThan":"9cd4b1a52eff330798d668c1775f8bc450776280","versionType":"git"},{"version":"29cb80519689706387bde47000dbb2ed91143063","status":"affected","lessThan":"f3530aec26563f4d483ff31402392961362e9bc6","versionType":"git"},{"version":"29cb80519689706387bde47000dbb2ed91143063","status":"affected","lessThan":"f73a8edc2ccc6ec72c37d5c578e7592d2e1f9922","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/arm64/mm/hugetlbpage.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.16","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.16","versionType":"semver"},{"version":"6.18.42","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.6","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/arm64/mm/hugetlbpage.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/9cd4b1a52eff330798d668c1775f8bc450776280"},{"url":"https://git.kernel.org/stable/c/f3530aec26563f4d483ff31402392961362e9bc6"},{"url":"https://git.kernel.org/stable/c/f73a8edc2ccc6ec72c37d5c578e7592d2e1f9922"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H","baseScore":7.1,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The bug is in arm64 huge_ptep_get(), reached only from local kernel entry points such as the mincore(2) syscall, hugetlb page-fault handling, and reading /proc/self/pagemap or smaps; there is no network, adjacent-radio, or physical-device path to this code.\nAC:L - On affected arm64 16K kernels with HugeTLB, an unprivileged process can mmap a contiguous-PMD (1G) hugetlb mapping and reliably trigger the bug via mincore() or a write fault at a page-aligned but contpmd-unaligned virtual address; no race or victim state outside attacker control is required.\nPR:L - Exploitation requires only a local unprivileged user who can invoke syscalls and access its own address space (/proc/self/pagemap and mincore on self mappings); no real root, CAP_SYS_ADMIN, or cross-user ptrace privileges are needed.\nUI:N - Triggering the flaw needs no action from another user or administrator beyond the attacker running its own syscalls against hugetlb mappings it created; no mount, file-open, or click-through by a victim is required.\nS:U - Impact is a kernel oops/panic and possible kernel page-table reads within the same kernel security authority; it does not cross VM, container, or IOMMU boundaries to compromise a separate security domain.\nC:H - Misclassifying a contpmd mapping causes huge_ptep_get() to iterate CONT_PTES times over advancing ptep pointers, reading PTE values beyond the valid table and potentially disclosing adjacent kernel page-table/physical-address data before dereferencing an unmapped linear-map address.\nI:N - The defective path only performs out-of-bounds PTE reads via __ptep_get(); it does not corrupt or write memory, modify page tables, or achieve code execution—only incorrect aggregation of accessed/dirty bits and eventual fatal dereference.\nA:H - Iteration can advance ptep into unmapped linear-map holes or past valid kernel mappings, causing an unhandled kernel page fault and system panic/oops, yielding complete loss of kernel availability on affected arm64 16K HugeTLB systems."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-17T05:00:12.926Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.16","versionEndExcluding":"6.18.42"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.16","versionEndExcluding":"7.1.6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.16","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}