CVE-2025-40190

Full vulnerability record from the local CVENow database.

Description

In the Linux kernel, the following vulnerability has been resolved: ext4: guard against EA inode refcount underflow in xattr update syzkaller found a path where ext4_xattr_inode_update_ref() reads an EA inode refcount that is already <= 0 and then applies ref_change (often -1). That lets the refcount underflow and we proceed with a bogus value, triggering errors like: EXT4-fs error: EA inode <n> ref underflow: ref_count=-1 ref_change=-1 EXT4-fs warning: ea_inode dec ref err=-117 Make the invariant explicit: if the current refcount is non-positive, treat this as on-disk corruption, emit ext4_error_inode(), and fail the operation with -EFSCORRUPTED instead of updating the refcount. Delete the WARN_ONCE() as negative refcounts are now impossible; keep error reporting in ext4_error_inode(). This prevents the underflow and the follow-on orphan/cleanup churn.

Severity

HIGH

CVSS score

7.8 (v3.1)

Vulnerability status

Deferred

Source identifier

416baaa9-dc9f-4396-8d5f-8c081fb06d67

Published

2025-11-12 22:15:45.960000

Last modified

2026-10-19 21:10:00.160000

View original CVE JSON

{
  "id": "CVE-2025-40190",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "published": "2025-11-12T22:15:45.960",
  "lastModified": "2026-10-19T21:10:00.160",
  "vulnStatus": "Deferred",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\next4: guard against EA inode refcount underflow in xattr update\n\nsyzkaller found a path where ext4_xattr_inode_update_ref() reads an EA\ninode refcount that is already <= 0 and then applies ref_change (often\n-1). That lets the refcount underflow and we proceed with a bogus value,\ntriggering errors like:\n\n  EXT4-fs error: EA inode <n> ref underflow: ref_count=-1 ref_change=-1\n  EXT4-fs warning: ea_inode dec ref err=-117\n\nMake the invariant explicit: if the current refcount is non-positive,\ntreat this as on-disk corruption, emit ext4_error_inode(), and fail the\noperation with -EFSCORRUPTED instead of updating the refcount. Delete the\nWARN_ONCE() as negative refcounts are now impossible; keep error reporting\nin ext4_error_inode().\n\nThis prevents the underflow and the follow-on orphan/cleanup churn."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\next4: protección contra el desbordamiento negativo del contador de referencias del inodo EA en la actualización de xattr\n\nsyzkaller encontró una ruta donde ext4_xattr_inode_update_ref() lee un contador de referencias del inodo EA que ya es menor o igual que 0 y luego aplica ref_change (a menudo -1). Esto permite el desbordamiento negativo del contador de referencias y se procede con un valor erróneo, desencadenando errores como:\n\n  EXT4-fs error: EA inode <n> desbordamiento negativo de ref: ref_count=-1 ref_change=-1\n  EXT4-fs warning: ea_inode dec ref err=-117\n\nHacer explícito el invariante: si el contador de referencias actual no es positivo, tratar esto como corrupción en disco, emitir ext4_error_inode(), y fallar la operación con -EFSCORRUPTED en lugar de actualizar el contador de referencias. Eliminar el WARN_ONCE() ya que los contadores de referencias negativos son ahora imposibles; mantener el informe de errores en ext4_error_inode().\n\nEsto previene el desbordamiento negativo y la posterior agitación de huérfanos/limpieza."
    }
  ],
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "programFiles": [
            "fs/ext4/xattr.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "lessThan": "ea39e712c2f5ae148ee5515798ae03523673e002",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "lessThan": "1cfb3e4ddbdc8e02e637b8852540bd4718bf4814",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "lessThan": "505e69f76ac497e788f4ea0267826ec7266b40c8",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "lessThan": "3d6269028246f4484bfed403c947a114bb583631",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "lessThan": "79ea7f3e11effe1bd9e753172981d9029133a278",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "lessThan": "6b879c4c6bbaab03c0ad2a983953bd1410bb165e",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "lessThan": "440b003f449a4ff2a00b08c8eab9ba5cd28f3943",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "lessThan": "57295e835408d8d425bef58da5253465db3d6888",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "0",
              "lessThan": "5.4.301",
              "versionType": "semver",
              "status": "affected"
            },
            {
              "version": "0",
              "lessThan": "5.10.246",
              "versionType": "semver",
              "status": "affected"
            },
            {
              "version": "0",
              "lessThan": "5.15.195",
              "versionType": "semver",
              "status": "affected"
            },
            {
              "version": "0",
              "lessThan": "6.1.157",
              "versionType": "semver",
              "status": "affected"
            },
            {
              "version": "0",
              "lessThan": "6.6.113",
              "versionType": "semver",
              "status": "affected"
            },
            {
              "version": "0",
              "lessThan": "6.12.54",
              "versionType": "semver",
              "status": "affected"
            },
            {
              "version": "0",
              "lessThan": "6.17.4",
              "versionType": "semver",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "programFiles": [
            "fs/ext4/xattr.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "5.4.301",
              "lessThanOrEqual": "5.4.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "5.10.246",
              "lessThanOrEqual": "5.10.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "5.15.195",
              "lessThanOrEqual": "5.15.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.1.157",
              "lessThanOrEqual": "6.1.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.6.113",
              "lessThanOrEqual": "6.6.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.12.54",
              "lessThanOrEqual": "6.12.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.17.4",
              "lessThanOrEqual": "6.17.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.18",
              "lessThanOrEqual": "*",
              "versionType": "original_commit_for_fix",
              "status": "unaffected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV31": [
      {
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary",
        "cvssData": {
          "version": "3.1",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
          "baseScore": 7.8,
          "baseSeverity": "HIGH",
          "attackVector": "LOCAL",
          "attackComplexity": "LOW",
          "privilegesRequired": "NONE",
          "userInteraction": "REQUIRED",
          "scope": "UNCHANGED",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "availabilityImpact": "HIGH"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 5.9
      }
    ]
  },
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/1cfb3e4ddbdc8e02e637b8852540bd4718bf4814",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/3d6269028246f4484bfed403c947a114bb583631",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/440b003f449a4ff2a00b08c8eab9ba5cd28f3943",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/505e69f76ac497e788f4ea0267826ec7266b40c8",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/57295e835408d8d425bef58da5253465db3d6888",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/6b879c4c6bbaab03c0ad2a983953bd1410bb165e",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/79ea7f3e11effe1bd9e753172981d9029133a278",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/ea39e712c2f5ae148ee5515798ae03523673e002",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ]
}