Vulnerability-Lookup

FKIE_CVE-2026-6687

Vulnerability from fkie_nvd - Published: 2026-07-01 15:17 - Updated: 2026-07-02 14:38

Severity

7.6 (High) - CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Summary

FatFs R0.16 and earlier contains a stack overflow bug in f_getlabel() because exFAT label length (XDIR_NumLabel) is trusted without enforcing spec maximums. This maps to CWE-121 (Stack-based Buffer Overflow). Estimated CVSS v3.1 vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H (7.6, High). The estimated CISA SSVC vectors are Exploitation: PoC, Technical Impact: Total.

References

URL	Tags
44488dab-36db-4358-99f9-bc116477f914	https://elm-chan.org/fsw/ff/	Product
44488dab-36db-4358-99f9-bc116477f914	https://github.com/runZeroInc/vulns-2026-fatfs-chance	Third Party Advisory, Exploit
44488dab-36db-4358-99f9-bc116477f914	https://www.runzero.com/advisories/fatfs-exfat-label-len-of-cve-2026-6687/	Third Party Advisory
44488dab-36db-4358-99f9-bc116477f914	https://www.runzero.com/blog/fatfs-bugs/	Third Party Advisory, Exploit
134c704f-9b21-4f2e-91b3-4a467353bcc0	https://github.com/runZeroInc/vulns-2026-fatfs-chance	Third Party Advisory, Exploit

Impacted products

	Vendor	Product	Version
	elm-chan	fatfs	*

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "FatFs",
          "vendor": "ChaN",
          "versions": [
            {
              "lessThanOrEqual": "R0.16",
              "status": "affected",
              "version": "0",
              "versionType": "custom"
            }
          ]
        }
      ],
      "source": "44488dab-36db-4358-99f9-bc116477f914"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:elm-chan:fatfs:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "B99160BB-C4F5-4DA0-9FC9-0723E0633E00",
              "versionEndIncluding": "r0.16",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "FatFs R0.16 and earlier contains a stack overflow bug in f_getlabel() because exFAT label length (XDIR_NumLabel) is trusted without enforcing spec maximums. This maps to CWE-121 (Stack-based Buffer Overflow). Estimated CVSS v3.1 vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H (7.6, High). The estimated CISA SSVC vectors are Exploitation: PoC, Technical Impact: Total."
    }
  ],
  "id": "CVE-2026-6687",
  "lastModified": "2026-07-02T14:38:40.173",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "PHYSICAL",
          "availabilityImpact": "HIGH",
          "baseScore": 7.6,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "CHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 0.9,
        "impactScore": 6.0,
        "source": "44488dab-36db-4358-99f9-bc116477f914",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-6687",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-07-01T15:06:20.995228Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-07-01T15:17:12.870",
  "references": [
    {
      "source": "44488dab-36db-4358-99f9-bc116477f914",
      "tags": [
        "Product"
      ],
      "url": "https://elm-chan.org/fsw/ff/"
    },
    {
      "source": "44488dab-36db-4358-99f9-bc116477f914",
      "tags": [
        "Third Party Advisory",
        "Exploit"
      ],
      "url": "https://github.com/runZeroInc/vulns-2026-fatfs-chance"
    },
    {
      "source": "44488dab-36db-4358-99f9-bc116477f914",
      "tags": [
        "Third Party Advisory"
      ],
      "url": "https://www.runzero.com/advisories/fatfs-exfat-label-len-of-cve-2026-6687/"
    },
    {
      "source": "44488dab-36db-4358-99f9-bc116477f914",
      "tags": [
        "Third Party Advisory",
        "Exploit"
      ],
      "url": "https://www.runzero.com/blog/fatfs-bugs/"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "tags": [
        "Third Party Advisory",
        "Exploit"
      ],
      "url": "https://github.com/runZeroInc/vulns-2026-fatfs-chance"
    }
  ],
  "sourceIdentifier": "44488dab-36db-4358-99f9-bc116477f914",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-121"
        }
      ],
      "source": "44488dab-36db-4358-99f9-bc116477f914",
      "type": "Secondary"
    }
  ]
}

CVE-2026-6687 (GCVE-0-2026-6687)

Vulnerability from cvelistv5 – Published: 2026-07-01 13:57 – Updated: 2026-07-01 15:06

Title

FatFs Stack Buffer Overflow via Uncapped exFAT Label Length

Summary

Severity

7.6 (High)


                        
                          CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

SSVC

Exploitation: poc Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-07-01 15:06 UTC

CWE

CWE-121 - Stack-based buffer overflow

Assigner

runZero icscert root Scorecard

References

4 references

URL	Tags
https://www.runzero.com/blog/fatfs-bugs/	third-party-advisory
https://github.com/runZeroInc/vulns-2026-fatfs-chance	technical-description
https://elm-chan.org/fsw/ff/	product
https://www.runzero.com/advisories/fatfs-exfat-la…	third-party-advisory

Impacted products

1 product

Vendor	Product	Version
ChaN	FatFs	Affected: 0 , ≤ R0.16 (custom)

Date Public

2026-07-01 13:00

Credits

HD Moore of runZero, Inc. Tod Beardsley of runZero, Inc.

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-6687",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-07-01T15:06:20.995228Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-07-01T15:06:24.705Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/runZeroInc/vulns-2026-fatfs-chance"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "FatFs",
          "vendor": "ChaN",
          "versions": [
            {
              "lessThanOrEqual": "R0.16",
              "status": "affected",
              "version": "0",
              "versionType": "custom"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "HD Moore of runZero, Inc."
        },
        {
          "lang": "en",
          "type": "coordinator",
          "value": "Tod Beardsley of runZero, Inc."
        }
      ],
      "datePublic": "2026-07-01T13:00:00.000Z",
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "FatFs R0.16 and earlier contains a stack overflow bug in f_getlabel() because exFAT label length (XDIR_NumLabel) is trusted without enforcing spec maximums. This maps to CWE-121 (Stack-based Buffer Overflow). Estimated CVSS v3.1 vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H (7.6, High). The estimated CISA SSVC vectors are Exploitation: PoC, Technical Impact: Total."
            }
          ],
          "value": "FatFs R0.16 and earlier contains a stack overflow bug in f_getlabel() because exFAT label length (XDIR_NumLabel) is trusted without enforcing spec maximums. This maps to CWE-121 (Stack-based Buffer Overflow). Estimated CVSS v3.1 vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H (7.6, High). The estimated CISA SSVC vectors are Exploitation: PoC, Technical Impact: Total."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "PHYSICAL",
            "availabilityImpact": "HIGH",
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            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "CHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H",
            "version": "3.1"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
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      ],
      "problemTypes": [
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          "descriptions": [
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              "lang": "en",
              "type": "CWE"
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        "orgId": "44488dab-36db-4358-99f9-bc116477f914",
        "shortName": "runZero"
      },
      "references": [
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          "tags": [
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          ],
          "url": "https://www.runzero.com/blog/fatfs-bugs/"
        },
        {
          "tags": [
            "technical-description"
          ],
          "url": "https://github.com/runZeroInc/vulns-2026-fatfs-chance"
        },
        {
          "tags": [
            "product"
          ],
          "url": "https://elm-chan.org/fsw/ff/"
        },
        {
          "tags": [
            "third-party-advisory"
          ],
          "url": "https://www.runzero.com/advisories/fatfs-exfat-label-len-of-cve-2026-6687/"
        }
      ],
      "source": {
        "discovery": "UNKNOWN"
      },
      "title": "FatFs Stack Buffer Overflow via Uncapped exFAT Label Length",
      "x_generator": {
        "engine": "Vulnogram 1.0.2"
      }
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  },
  "cveMetadata": {
    "assignerOrgId": "44488dab-36db-4358-99f9-bc116477f914",
    "assignerShortName": "runZero",
    "cveId": "CVE-2026-6687",
    "datePublished": "2026-07-01T13:57:54.242Z",
    "dateReserved": "2026-04-20T15:06:23.356Z",
    "dateUpdated": "2026-07-01T15:06:24.705Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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.

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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FKIE_CVE-2026-6687

CVE-2026-6687 (GCVE-0-2026-6687)

Tags

Sightings

Nomenclature

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