Vulnerability-Lookup

GHSA-VJ97-73GP-638R

Vulnerability from github – Published: 2025-12-07 00:30 – Updated: 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": []
}

CVE-2025-40287 (GCVE-0-2025-40287)

Vulnerability from cvelistv5 – Published: 2025-12-06 21:51 – Updated: 2026-05-11 21:46

Title

exfat: fix improper check of dentry.stream.valid_size

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.

Severity

No CVSS data available.

Assigner

Linux mitre root

References

3 references

URL	Tags
https://git.kernel.org/stable/c/6c627bcc1896ba62e…
https://git.kernel.org/stable/c/204b1b02ee018ba52…
https://git.kernel.org/stable/c/82ebecdc74ff555da…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 11a347fb6cef62ce47e84b97c45f2b2497c7593b , < 6c627bcc1896ba62ec793d0c00da74f3c93ce3ad (git) Affected: 11a347fb6cef62ce47e84b97c45f2b2497c7593b , < 204b1b02ee018ba52ad2ece21fe3a8643d66a1b2 (git) Affected: 11a347fb6cef62ce47e84b97c45f2b2497c7593b , < 82ebecdc74ff555daf70b811d854b1f32a296bea (git)
Linux	Linux	Affected: 6.8 Unaffected: 0 , < 6.8 (semver) Unaffected: 6.12.59 , ≤ 6.12.* (semver) Unaffected: 6.17.9 , ≤ 6.17.* (semver) Unaffected: 6.18 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "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": [
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              "status": "affected",
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              "versionType": "git"
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              "version": "11a347fb6cef62ce47e84b97c45f2b2497c7593b",
              "versionType": "git"
            },
            {
              "lessThan": "82ebecdc74ff555daf70b811d854b1f32a296bea",
              "status": "affected",
              "version": "11a347fb6cef62ce47e84b97c45f2b2497c7593b",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/exfat/namei.c"
          ],
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          "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"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.59",
                  "versionStartIncluding": "6.8",
                  "vulnerable": true
                },
                {
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                  "versionStartIncluding": "6.8",
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                },
                {
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                  "versionStartIncluding": "6.8",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
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      "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."
        }
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      "providerMetadata": {
        "dateUpdated": "2026-05-11T21:46:25.955Z",
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      "title": "exfat: fix improper check of dentry.stream.valid_size",
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    "datePublished": "2025-12-06T21:51:13.328Z",
    "dateReserved": "2025-04-16T07:20:57.184Z",
    "dateUpdated": "2026-05-11T21:46:25.955Z",
    "state": "PUBLISHED"
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}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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