FKIE_CVE-2026-31694

Vulnerability from fkie_nvd - Published: 2026-05-01 14:16 - Updated: 2026-10-23 14:06
Severity
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: fuse: reject oversized dirents in page cache fuse_add_dirent_to_cache() computes a serialized dirent size from the server-controlled namelen field and copies the dirent into a single page-cache page. The existing logic only checks whether the dirent fits in the remaining space of the current page and advances to a fresh page if not. It never checks whether the dirent itself exceeds PAGE_SIZE. As a result, a malicious FUSE server can return a dirent with namelen=4095, producing a serialized record size of 4120 bytes. On 4 KiB page systems this causes memcpy() to overflow the cache page by 24 bytes into the following kernel page. Reject dirents that cannot fit in a single page before copying them into the readdir cache.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/474ce83c96a55f2eeb14dee2be375eeadfdacdf5Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/51a8de6c50bf947c8f534cd73da4c8f0a13e7bedPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/7de93abfaae1b2dc94da8a07a36421bd073f1d8fPatch
0b142b55-0307-4c5a-b3c9-f314f3fb7c5ehttps://cert-portal.siemens.com/productcert/html/ssa-784472.htmlThird Party Advisory
Impacted products
Vendor Product Version
linux linux_kernel *
linux linux_kernel *
linux linux_kernel 7.1
linux linux_kernel 7.1
siemens simatic_s7-1500_tm_mfp_firmware -
siemens simatic_s7-1500_tm_mfp -
To clipboard 

{
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          "product": "Linux",
          "programFiles": [
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    },
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          "vendor": "Siemens",
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              "versionType": "custom"
            }
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        }
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    }
  ],
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  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfuse: reject oversized dirents in page cache\n\nfuse_add_dirent_to_cache() computes a serialized dirent size from the\nserver-controlled namelen field and copies the dirent into a single\npage-cache page. The existing logic only checks whether the dirent fits\nin the remaining space of the current page and advances to a fresh page\nif not. It never checks whether the dirent itself exceeds PAGE_SIZE.\n\nAs a result, a malicious FUSE server can return a dirent with\nnamelen=4095, producing a serialized record size of 4120 bytes. On 4 KiB\npage systems this causes memcpy() to overflow the cache page by 24 bytes\ninto the following kernel page.\n\nReject dirents that cannot fit in a single page before copying them into\nthe readdir cache."
    }
  ],
  "id": "CVE-2026-31694",
  "lastModified": "2026-10-23T14:06:26.363",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 7.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
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        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
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  "published": "2026-05-01T14:16:19.133",
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  "vulnStatus": "Analyzed",
  "weaknesses": [
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        {
          "lang": "en",
          "value": "NVD-CWE-noinfo"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}



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