{
  "schemaVersion": 1,
  "attribution": [
    {
      "source": "CISA Known Exploited Vulnerabilities",
      "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog",
      "licence": "US government work"
    },
    {
      "source": "GitHub Advisory Database",
      "url": "https://github.com/advisories",
      "licence": "CC BY 4.0"
    },
    {
      "source": "Have I Been Pwned",
      "url": "https://haveibeenpwned.com/",
      "licence": "CC BY 4.0"
    },
    {
      "source": "CVE Program (CVE records)",
      "url": "https://www.cve.org/Legal/TermsOfUse",
      "licence": "CVE Terms of Use",
      "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.",
      "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy."
    },
    {
      "source": "FIRST EPSS",
      "url": "https://www.first.org/epss/",
      "licence": "free to use; FIRST requests attribution"
    }
  ],
  "record": {
    "id": "CVE-2025-39899",
    "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2025-39899",
    "idYear": 2025,
    "status": "PUBLISHED",
    "publishedAt": "2025-10-01T07:42:47.100Z",
    "updatedAt": "2026-05-11T21:38:33.572Z",
    "importedAt": "2026-10-24T01:57:34.152Z",
    "snapshot": {
      "id": "cve_2026-10-24_midnight_baseline",
      "at": "2026-10-24T00:00:00.000Z",
      "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z"
    },
    "facts": {
      "title": "mm/userfaultfd: fix kmap_local LIFO ordering for CONFIG_HIGHPTE",
      "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/userfaultfd: fix kmap_local LIFO ordering for CONFIG_HIGHPTE\n\nWith CONFIG_HIGHPTE on 32-bit ARM, move_pages_pte() maps PTE pages using\nkmap_local_page(), which requires unmapping in Last-In-First-Out order.\n\nThe current code maps dst_pte first, then src_pte, but unmaps them in the\nsame order (dst_pte, src_pte), violating the LIFO requirement.  This\ncauses the warning in kunmap_local_indexed():\n\n  WARNING: CPU: 0 PID: 604 at mm/highmem.c:622 kunmap_local_indexed+0x178/0x17c\n  addr \\!= __fix_to_virt(FIX_KMAP_BEGIN + idx)\n\nFix this by reversing the unmap order to respect LIFO ordering.\n\nThis issue follows the same pattern as similar fixes:\n- commit eca6828403b8 (\"crypto: skcipher - fix mismatch between mapping and unmapping order\")\n- commit 8cf57c6df818 (\"nilfs2: eliminate staggered calls to kunmap in nilfs_rename\")\n\nBoth of which addressed the same fundamental requirement that kmap_local\noperations must follow LIFO ordering.",
      "affected": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "adef440691bab824e39c1b17382322d195e1fab0",
              "status": "affected",
              "versionType": "git",
              "lessThan": "b051f707018967ea8f697d790a1ed8c443f63812"
            },
            {
              "version": "adef440691bab824e39c1b17382322d195e1fab0",
              "status": "affected",
              "versionType": "git",
              "lessThan": "bd1ee62759d0bd4d6b909731c076c230ac89d61e"
            },
            {
              "version": "adef440691bab824e39c1b17382322d195e1fab0",
              "status": "affected",
              "versionType": "git",
              "lessThan": "9614d8bee66387501f48718fa306e17f2aa3f2f3"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "versions": [
            {
              "version": "6.8",
              "status": "affected"
            },
            {
              "version": "0",
              "status": "unaffected",
              "versionType": "semver",
              "lessThan": "6.8"
            },
            {
              "version": "6.12.46",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "version": "6.16.6",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "6.16.*"
            },
            {
              "version": "6.17",
              "status": "unaffected",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ]
        }
      ]
    }
  }
}