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GHSA-MC2F-CM9P-679Q

Vulnerability from github – Published: 2026-08-10 15:33 – Updated: 2026-08-14 00:31

Details

In the Linux kernel, the following vulnerability has been resolved:

arm64: make huge_ptep_get handled unaligned addresses

huge_ptep_get() can be handed a virtual address pointing to the middle of a contpmd/contpte mapped hugetlb folio (examples of callers are pagemap_hugetlb_range, page_mapped_in_vma).

The arm64 helper rewalks the pgtables in find_num_contig to answer whether the huge pte we have maps a contpmd or a contpte hugetlb folio, and returns CONT_PMDS or CONT_PTES, so that it can collect a/d bits over the contiguous ptes. We can falsely return CONT_PTES instead of CONT_PMDS if the addr is not aligned. On systems where CONT_PTES != CONT_PMDS (meaning page size is 16K), we could collect excess A/D bit state, meaning extra work for the kernel. Even worse, we may iterate beyond the PTE table and dereference a garbage ptep pointer to access physical memory we don't own. Since the ptep pointer is a linear map address, we may run off the end of the linear map or into a hole, dereference a VA not mapped into the kernel pgtables and cause kernel panic.

Fix this by aligning the pmdp pointer down to a contpmd base before checking equality with the passed huge pte pointer, to correctly answer whether the huge pte is the base of a contpmd block.

Severity

7.1 (High)


                  
                    CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

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{
  "affected": [],
  "aliases": [
    "CVE-2026-68172"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-10T13:20:03Z",
    "severity": "HIGH"
  },
  "details": "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\u0027t 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.",
  "id": "GHSA-mc2f-cm9p-679q",
  "modified": "2026-08-14T00:31:52Z",
  "published": "2026-08-10T15:33:39Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-68172"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9cd4b1a52eff330798d668c1775f8bc450776280"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f3530aec26563f4d483ff31402392961362e9bc6"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f73a8edc2ccc6ec72c37d5c578e7592d2e1f9922"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-68172 (GCVE-0-2026-68172)

Vulnerability from cvelistv5 – Published: 2026-08-10 11:59 – Updated: 2026-08-17 05:00

Title

arm64: make huge_ptep_get handled unaligned addresses

Summary

In the Linux kernel, the following vulnerability has been resolved: arm64: make huge_ptep_get handled unaligned addresses huge_ptep_get() can be handed a virtual address pointing to the middle of a contpmd/contpte mapped hugetlb folio (examples of callers are pagemap_hugetlb_range, page_mapped_in_vma). The arm64 helper rewalks the pgtables in find_num_contig to answer whether the huge pte we have maps a contpmd or a contpte hugetlb folio, and returns CONT_PMDS or CONT_PTES, so that it can collect a/d bits over the contiguous ptes. We can falsely return CONT_PTES instead of CONT_PMDS if the addr is not aligned. On systems where CONT_PTES != CONT_PMDS (meaning page size is 16K), we could collect excess A/D bit state, meaning extra work for the kernel. Even worse, we may iterate beyond the PTE table and dereference a garbage ptep pointer to access physical memory we don't own. Since the ptep pointer is a linear map address, we may run off the end of the linear map or into a hole, dereference a VA not mapped into the kernel pgtables and cause kernel panic. Fix this by aligning the pmdp pointer down to a contpmd base before checking equality with the passed huge pte pointer, to correctly answer whether the huge pte is the base of a contpmd block.

Severity

7.1 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

Assigner

Linux mitre root

References

3 references

URL	Tags
https://git.kernel.org/stable/c/9cd4b1a52eff33079…
https://git.kernel.org/stable/c/f3530aec26563f4d4…
https://git.kernel.org/stable/c/f73a8edc2ccc6ec72…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 29cb80519689706387bde47000dbb2ed91143063 , < 9cd4b1a52eff330798d668c1775f8bc450776280 (git) Affected: 29cb80519689706387bde47000dbb2ed91143063 , < f3530aec26563f4d483ff31402392961362e9bc6 (git) Affected: 29cb80519689706387bde47000dbb2ed91143063 , < f73a8edc2ccc6ec72c37d5c578e7592d2e1f9922 (git)
Linux	Linux	Affected: 6.16 Unaffected: 0 , < 6.16 (semver) Unaffected: 6.18.42 , ≤ 6.18.* (semver) Unaffected: 7.1.6 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/arm64/mm/hugetlbpage.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "9cd4b1a52eff330798d668c1775f8bc450776280",
              "status": "affected",
              "version": "29cb80519689706387bde47000dbb2ed91143063",
              "versionType": "git"
            },
            {
              "lessThan": "f3530aec26563f4d483ff31402392961362e9bc6",
              "status": "affected",
              "version": "29cb80519689706387bde47000dbb2ed91143063",
              "versionType": "git"
            },
            {
              "lessThan": "f73a8edc2ccc6ec72c37d5c578e7592d2e1f9922",
              "status": "affected",
              "version": "29cb80519689706387bde47000dbb2ed91143063",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "arch/arm64/mm/hugetlbpage.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.16"
            },
            {
              "lessThan": "6.16",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.42",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.42",
                  "versionStartIncluding": "6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.6",
                  "versionStartIncluding": "6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "6.16",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "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\u0027t 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."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.1,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
            "version": "3.1"
          },
          "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\u2014only 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": {
        "dateUpdated": "2026-08-17T05:00:12.926Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "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"
        }
      ],
      "title": "arm64: make huge_ptep_get handled unaligned addresses",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-68172",
    "datePublished": "2026-08-10T11:59:41.893Z",
    "dateReserved": "2026-07-30T09:28:09.372Z",
    "dateUpdated": "2026-08-17T05:00:12.926Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

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GHSA-MC2F-CM9P-679Q

CVE-2026-68172 (GCVE-0-2026-68172)

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Sightings

Nomenclature