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CVE-2026-97525

📛 CVE Title

x86/mm/pat: Allocate split page tables as kernel page tables

Description

In the Linux kernel, the following vulnerability has been resolved: x86/mm/pat: Allocate split page tables as kernel page tables A PTE is allocated directly without going through the standard page table allocation routines (such as pte_alloc_one_kernel()) when the CPA code splits a large page (__split_large_page()). This means the page table constructor is never called nor is the page table marked as a kernel page table. The former results in the folio associated with the page table not being marked as a page table (__pagetable_ctor() is never called thus neither is __folio_set_pgtable()) nor are statistics updated to reflect it (lruvec_stat_add_folio() is never called). The latter issue of failing to mark the page table as a kernel page table (ptdesc_set_kernel() is never called) is far more problematic. Since commit: 5ba2f0a15564 ("mm: introduce deferred freeing for kernel page tables") kernel page table freeing has been batched and since the subsequent commit: e37d5a2d60a3 ("iommu/sva: invalidate stale IOTLB entries for kernel address space") IOTLB cache entries for kernel page tables have been invalidated upon being freed. Since split page tables are freed without this invalidation, the IOTLB can contain stale entries for them. Resolve the issue by using the ordinary PTE allocation API at split time. This results in these kernel page tables invoking a page table constructor, and thus requires a page table destructor. Destructors are not always present, like for early allocated direct map page tables). Conditionally call pagetable_dtor_free() if the PG_table folio flag for the ptdesc is set, otherwise we free the page table via pagetable_free(). Regardless of which path is taken page tables marked as kernel page tables, which now includes split page tables, take the correct route through pagetable_free_kernel(). There is a user-visible side effect in that split page tables will appear in nr_page_table_pages in /proc/vmstat (as do other kernel page tables allocated after early boot), however this is a positive change. This issue started being markedly problematic after commit: 5ba2f0a15564 ("mm: introduce deferred freeing for kernel page tables") so choose this as the Fixes target. [ dhansen: rephrase in imperative mood ]

Overview

State
PUBLISHED
Assigner (CNA)
Linux
CVSS severity
HIGH
CVSS score
CVSS 8.2 / 10 8.2 8.2 / 10
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
Effective score
8.2 / 10 HIGH source: CNA overview
CWE(s)
—
Reserved
2026-09-24
Published
2026-09-25 10:21 UTC
Last updated
2026-09-25 14:41 UTC
Source
https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/97xxx/CVE-2026-97525.json
Linked Threat
CVE-2026-97525 — x86/mm/pat: Allocate split page tables as kernel page tables

NVD triage scoring NVD CVE 2.0

Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.

NVD published
2026-09-25 11:17:02 UTC
NVD last modified
2026-09-25 15:17:57 UTC
NVD CVSS v3.1
CVSS 8.2 / 10 8.2 8.2 / 10 HIGH source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD CVSS vector
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
Exploitability subscore
1.5 / 10
Impact subscore
6.0 / 10

NVD / KEV / EPSS data refreshed 2026-09-26 04:35 UTC. Re-run the 🛰 Backfill from NVD button above to refresh.

Affected products (2)

VendorProductVersionsPlatforms
Linux Linux b3039c526f3e1744db0cbb7ae1f0213f5e27d3f4 (affected), 5ba2f0a1556479638ac11a3c201421f5515e89f5 (affected), 5ba2f0a1556479638ac11a3c201421f5515e89f5 (affected), 6.18.7 (affected) —
Linux Linux 6.19 (affected), 0 (unaffected), 6.18.53 (unaffected), 7.2.7 (unaffected), 7.3-rc4 (unaffected) —

Vendor references (3)

References embedded in the original CVE record by the assigning CNA.

Web references (0)

DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.

No web references attached yet.

NVD-tagged references (3)

Reference list NVD curates from the CNA record, vendor advisories, and third-party reports. The tag chips below are NVD's analyst-assigned categories.

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Raw JSON

The full cvelistV5 record. Download as CVE-2026-97525.json.

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/x86/mm/pat/set_memory.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "84e0cd79d57f06b872154eb5d8f610584133f260",
              "status": "affected",
              "version": "b3039c526f3e1744db0cbb7ae1f0213f5e27d3f4",
              "versionType": "git"
            },
            {
              "lessThan": "922873cf4fc34124215070a8ad391bf831538bb9",
              "status": "affected",
              "version": "5ba2f0a1556479638ac11a3c201421f5515e89f5",
              "versionType": "git"
            },
            {
              "lessThan": "9e4a3ec3411bb6bb59e3c1f29b75609f1e87aac4",
              "status": "affected",
              "version": "5ba2f0a1556479638ac11a3c201421f5515e89f5",
              "versionType": "git"
            },
            {
              "lessThan": "6.18.53",
              "status": "affected",
              "version": "6.18.7",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "arch/x86/mm/pat/set_memory.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.19"
            },
            {
              "lessThan": "6.19",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.53",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.7",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc4",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.53",
                  "versionStartIncluding": "6.18.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.7",
                  "versionStartIncluding": "6.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3-rc4",
                  "versionStartIncluding": "6.19",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nx86/mm/pat: Allocate split page tables as kernel page tables\n\nA PTE is allocated directly without going through the standard page table\nallocation routines (such as pte_alloc_one_kernel()) when the CPA code\nsplits a large page (__split_large_page()).\n\nThis means the page table constructor is never called nor is the page table\nmarked as a kernel page table.\n\nThe former results in the folio associated with the page table not being\nmarked as a page table (__pagetable_ctor() is never called thus neither is\n__folio_set_pgtable()) nor are statistics updated to reflect\nit (lruvec_stat_add_folio() is never called).\n\nThe latter issue of failing to mark the page table as a kernel page\ntable (ptdesc_set_kernel() is never called) is far more problematic.\n\nSince commit:\n\n  5ba2f0a15564 (\"mm: introduce deferred freeing for kernel page tables\")\n\nkernel page table freeing has been batched and since the\nsubsequent commit:\n\n  e37d5a2d60a3 (\"iommu/sva: invalidate stale IOTLB entries for kernel address space\")\n\nIOTLB cache entries for kernel page tables have been invalidated upon\nbeing freed.\n\nSince split page tables are freed without this invalidation, the IOTLB\ncan contain stale entries for them.\n\nResolve the issue by using the ordinary PTE allocation API at split time.\n\nThis results in these kernel page tables invoking a page table constructor,\nand thus requires a page table destructor.\n\nDestructors are not always present, like for early allocated direct map\npage tables). Conditionally call pagetable_dtor_free() if the PG_table\nfolio flag for the ptdesc is set, otherwise we free the page table via\npagetable_free().\n\nRegardless of which path is taken page tables marked as kernel page tables,\nwhich now includes split page tables, take the correct route through\npagetable_free_kernel().\n\nThere is a user-visible side effect in that split page tables will appear\nin nr_page_table_pages in /proc/vmstat (as do other kernel page tables\nallocated after early boot), however this is a positive change.\n\nThis issue started being markedly problematic after commit:\n\n  5ba2f0a15564 (\"mm: introduce deferred freeing for kernel page tables\")\n\nso choose this as the Fixes target.\n\n[ dhansen: rephrase in imperative mood ]"
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.2,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - split_large_page() is reached from local set_memory_* via change_page_attr_set_clr()\u2192__change_page_attr(); the path that allocates unmarked tables and later frees them is finit_module\u2192module_memory_alloc()\u2192execmem_alloc_rw()\u2192execmem_force_rw()/set_memory_nx (split) then module_enable_text_rox()\u2192set_memory_rox() (collapse). No remote protocol carries the input.\nAC:L - On an x86 IOMMU_SVA host, a module whose text is carved from the execmem ROX 2M cache makes execmem_force_rw() split that PMD (pagetable_alloc without ptdesc_set_kernel) and set_memory_rox(CPA_COLLAPSE) free it in cpa_collapse_large_pages(); the same caller binds SVA, primes IOTLB walks, and sprays reuse without an uncontrolled race.\nPR:H - may_init_module() requires capable(CAP_SYS_MODULE) in init_user_ns, which user namespaces cannot grant. Only EXECMEM_MODULE_TEXT with EXECMEM_ROX_CACHE both splits a huge mapping in split_large_page() and collapse-frees it; EXECMEM_BPF lacks ROX_CACHE so unprivileged bpf_jit_alloc_exec()/set_memory_rox does not produce these unmarked tables.\nUI:N - The attacker issues their own init_module/finit_module (and optional delete_module) against a module they supply; no other user must mount an image, open a file, or bind a device on their behalf.\nS:C - cpa_collapse_large_pages() calls pagetable_free() on the PTE table split_large_page() allocated without ptdesc_set_kernel(), so ptdesc_test_kernel() is false and pagetable_free_kernel() never runs iommu_sva_invalidate_kva_range(); a PASID SVA walk can treat the reused page as IOMMU translations, crossing the IOMMU DMA isolation boundary.\nC:H - A stale IOTLB paging-structure cache entry for the freed split table lets the IOMMU interpret attacker-controlled reused page contents as PTEs, enabling arbitrary physical-memory DMA reads of kernel or other-process data.\nI:H - The same stale IOTLB walk enables arbitrary physical-memory DMA writes, and the IOMMU may write Accessed and Dirty bits into the recycled page while walking it, a write-after-free of the unmarked CPA table.\nA:H - Arbitrary DMA writes into reused memory and IOTLB write-after-free of the page cpa_collapse_large_pages() passed to pagetable_free() can corrupt kernel or page-table state, causing an oops, panic, or hang."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-25T14:41:06.479Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/84e0cd79d57f06b872154eb5d8f610584133f260"
        },
        {
          "url": "https://git.kernel.org/stable/c/922873cf4fc34124215070a8ad391bf831538bb9"
        },
        {
          "url": "https://git.kernel.org/stable/c/9e4a3ec3411bb6bb59e3c1f29b75609f1e87aac4"
        }
      ],
      "title": "x86/mm/pat: Allocate split page tables as kernel page tables",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-97525",
    "datePublished": "2026-09-25T10:21:28.284Z",
    "dateReserved": "2026-09-24T16:01:01.152Z",
    "dateUpdated": "2026-09-25T14:41:06.479Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}