FKIE_CVE-2025-21696

Vulnerability from fkie_nvd - Published: 2025-02-12 14:15 - Updated: 2026-06-17 08:44
Severity
5.5 (Medium) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5 (Medium) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: mm: clear uffd-wp PTE/PMD state on mremap() When mremap()ing a memory region previously registered with userfaultfd as write-protected but without UFFD_FEATURE_EVENT_REMAP, an inconsistency in flag clearing leads to a mismatch between the vma flags (which have uffd-wp cleared) and the pte/pmd flags (which do not have uffd-wp cleared). This mismatch causes a subsequent mprotect(PROT_WRITE) to trigger a warning in page_table_check_pte_flags() due to setting the pte to writable while uffd-wp is still set. Fix this by always explicitly clearing the uffd-wp pte/pmd flags on any such mremap() so that the values are consistent with the existing clearing of VM_UFFD_WP. Be careful to clear the logical flag regardless of its physical form; a PTE bit, a swap PTE bit, or a PTE marker. Cover PTE, huge PMD and hugetlb paths.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/0cef0bb836e3cfe00f08f9606c72abd72fe78ca3Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/310ac886d68de661c3a334198d8604b722d7fdf8Patch
Impacted products
Vendor Product Version
linux linux_kernel *
linux linux_kernel 6.13
linux linux_kernel 6.13
linux linux_kernel 6.13
linux linux_kernel 6.13
linux linux_kernel 6.13
linux linux_kernel 6.13
linux linux_kernel 6.13
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "include/linux/userfaultfd_k.h",
            "mm/huge_memory.c",
            "mm/hugetlb.c",
            "mm/mremap.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "310ac886d68de661c3a334198d8604b722d7fdf8",
              "status": "affected",
              "version": "63b2d4174c4ad1f40b48d7138e71bcb564c1fe03",
              "versionType": "git"
            },
            {
              "lessThan": "0cef0bb836e3cfe00f08f9606c72abd72fe78ca3",
              "status": "affected",
              "version": "63b2d4174c4ad1f40b48d7138e71bcb564c1fe03",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "include/linux/userfaultfd_k.h",
            "mm/huge_memory.c",
            "mm/hugetlb.c",
            "mm/mremap.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.7"
            },
            {
              "lessThan": "5.7",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.11",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.13",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
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              "matchCriteriaId": "5D417CD4-B1C8-4FE8-8AF0-A83BA4A02112",
              "versionEndExcluding": "6.12.11",
              "versionStartIncluding": "5.7",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:6.13:rc1:*:*:*:*:*:*",
              "matchCriteriaId": "62567B3C-6CEE-46D0-BC2E-B3717FBF7D13",
              "vulnerable": true
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              "matchCriteriaId": "5A073481-106D-4B15-B4C7-FB0213B8E1D4",
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              "criteria": "cpe:2.3:o:linux:linux_kernel:6.13:rc5:*:*:*:*:*:*",
              "matchCriteriaId": "034C36A6-C481-41F3-AE9A-D116E5BE6895",
              "vulnerable": true
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            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:6.13:rc6:*:*:*:*:*:*",
              "matchCriteriaId": "8AF9DC49-2085-4FFB-A7E3-73DFAFECC7F2",
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            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:6.13:rc7:*:*:*:*:*:*",
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              "vulnerable": true
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          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm: clear uffd-wp PTE/PMD state on mremap()\n\nWhen mremap()ing a memory region previously registered with userfaultfd as\nwrite-protected but without UFFD_FEATURE_EVENT_REMAP, an inconsistency in\nflag clearing leads to a mismatch between the vma flags (which have\nuffd-wp cleared) and the pte/pmd flags (which do not have uffd-wp\ncleared).  This mismatch causes a subsequent mprotect(PROT_WRITE) to\ntrigger a warning in page_table_check_pte_flags() due to setting the pte\nto writable while uffd-wp is still set.\n\nFix this by always explicitly clearing the uffd-wp pte/pmd flags on any\nsuch mremap() so that the values are consistent with the existing clearing\nof VM_UFFD_WP.  Be careful to clear the logical flag regardless of its\nphysical form; a PTE bit, a swap PTE bit, or a PTE marker.  Cover PTE,\nhuge PMD and hugetlb paths."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: mm: borrar el estado PTE/PMD de uffd-wp en mremap() Al borrar con mremap() una regi\u00f3n de memoria registrada previamente con userfaultfd como protegida contra escritura pero sin UFFD_FEATURE_EVENT_REMAP, una inconsistencia en la depuraci\u00f3n de indicadores provoca una falta de coincidencia entre los indicadores vma (que tienen uffd-wp borrado) y los indicadores pte/pmd (que no tienen uffd-wp borrado). Esta falta de coincidencia hace que un mprotect(PROT_WRITE) posterior active una advertencia en page_table_check_pte_flags() debido a la configuraci\u00f3n de pte como escribible mientras uffd-wp a\u00fan est\u00e1 configurado. Solucione esto borrando siempre expl\u00edcitamente los indicadores pte/pmd de uffd-wp en cualquier mremap() de este tipo para que los valores sean coherentes con la depuraci\u00f3n existente de VM_UFFD_WP. Tenga cuidado de borrar el indicador l\u00f3gico independientemente de su forma f\u00edsica: un bit PTE, un bit PTE de intercambio o un marcador PTE. Cubra las rutas PTE, PMD enormes y TLB enormes."
    }
  ],
  "id": "CVE-2025-21696",
  "lastModified": "2026-06-17T08:44:03.017",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 5.5,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 3.6,
        "source": "nvd@nist.gov",
        "type": "Primary"
      },
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 5.5,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 3.6,
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2025-21696",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2025-10-01T19:51:14.846865Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2025-02-12T14:15:32.677",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/0cef0bb836e3cfe00f08f9606c72abd72fe78ca3"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/310ac886d68de661c3a334198d8604b722d7fdf8"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "NVD-CWE-noinfo"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}


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