FKIE_CVE-2025-40287

Vulnerability from fkie_nvd - Published: 2025-12-06 22:15 - Updated: 2026-10-15 19:10
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: exfat: fix improper check of dentry.stream.valid_size We found an infinite loop bug in the exFAT file system that can lead to a Denial-of-Service (DoS) condition. When a dentry in an exFAT filesystem is malformed, the following system calls — SYS_openat, SYS_ftruncate, and SYS_pwrite64 — can cause the kernel to hang. Root cause analysis shows that the size validation code in exfat_find() does not check whether dentry.stream.valid_size is negative. As a result, the system calls mentioned above can succeed and eventually trigger the DoS issue. This patch adds a check for negative dentry.stream.valid_size to prevent this vulnerability.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/204b1b02ee018ba52ad2ece21fe3a8643d66a1b2
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/6c627bcc1896ba62ec793d0c00da74f3c93ce3ad
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/82ebecdc74ff555daf70b811d854b1f32a296bea
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/exfat/namei.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "6c627bcc1896ba62ec793d0c00da74f3c93ce3ad",
              "status": "affected",
              "version": "11a347fb6cef62ce47e84b97c45f2b2497c7593b",
              "versionType": "git"
            },
            {
              "lessThan": "204b1b02ee018ba52ad2ece21fe3a8643d66a1b2",
              "status": "affected",
              "version": "11a347fb6cef62ce47e84b97c45f2b2497c7593b",
              "versionType": "git"
            },
            {
              "lessThan": "82ebecdc74ff555daf70b811d854b1f32a296bea",
              "status": "affected",
              "version": "11a347fb6cef62ce47e84b97c45f2b2497c7593b",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/exfat/namei.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.8"
            },
            {
              "lessThan": "6.8",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.59",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.17.*",
              "status": "unaffected",
              "version": "6.17.9",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.18",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nexfat: fix improper check of dentry.stream.valid_size\n\nWe found an infinite loop bug in the exFAT file system that can lead to a\nDenial-of-Service (DoS) condition. When a dentry in an exFAT filesystem is\nmalformed, the following system calls \u2014 SYS_openat, SYS_ftruncate, and\nSYS_pwrite64 \u2014 can cause the kernel to hang.\n\nRoot cause analysis shows that the size validation code in exfat_find()\ndoes not check whether dentry.stream.valid_size is negative. As a result,\nthe system calls mentioned above can succeed and eventually trigger the DoS\nissue.\n\nThis patch adds a check for negative dentry.stream.valid_size to prevent\nthis vulnerability."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nexfat: corrige la comprobaci\u00f3n incorrecta de dentry.stream.valid_size\n\nHemos encontrado un error de bucle infinito en el sistema de archivos exFAT que puede conducir a una condici\u00f3n de Denegaci\u00f3n de Servicio (DoS). Cuando una dentry en un sistema de archivos exFAT est\u00e1 malformada, las siguientes llamadas al sistema - SYS_openat, SYS_ftruncate y SYS_pwrite64 - pueden hacer que el kernel se cuelgue.\n\nEl an\u00e1lisis de la causa ra\u00edz muestra que el c\u00f3digo de validaci\u00f3n de tama\u00f1o en exfat_find() no comprueba si dentry.stream.valid_size es negativo. Como resultado, las llamadas al sistema mencionadas anteriormente pueden tener \u00e9xito y eventualmente desencadenar el problema de DoS.\n\nEste parche a\u00f1ade una comprobaci\u00f3n para dentry.stream.valid_size negativo para prevenir esta vulnerabilidad."
    }
  ],
  "id": "CVE-2025-40287",
  "lastModified": "2026-10-15T19:10:00.173",
  "metrics": {},
  "published": "2025-12-06T22:15:56.927",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/204b1b02ee018ba52ad2ece21fe3a8643d66a1b2"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/6c627bcc1896ba62ec793d0c00da74f3c93ce3ad"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/82ebecdc74ff555daf70b811d854b1f32a296bea"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Deferred"
}



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