ghsa-vj97-73gp-638r
Vulnerability from github
Published
2025-12-07 00:30
Modified
2025-12-07 00:30
Details

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.

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{
  "affected": [],
  "aliases": [
    "CVE-2025-40287"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-12-06T22:15:56Z",
    "severity": null
  },
  "details": "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.",
  "id": "GHSA-vj97-73gp-638r",
  "modified": "2025-12-07T00:30:56Z",
  "published": "2025-12-07T00:30:56Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-40287"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/204b1b02ee018ba52ad2ece21fe3a8643d66a1b2"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6c627bcc1896ba62ec793d0c00da74f3c93ce3ad"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/82ebecdc74ff555daf70b811d854b1f32a296bea"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}


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