Vulnerability-Lookup

GHSA-H94P-VJQX-V7RR

Vulnerability from github – Published: 2026-07-01 15:35 – Updated: 2026-07-01 15:35

Details

FatFs R0.16 and earlier contains an uninitialized cluster exposure when f_lseek() extends files beyond EOF without zero-filling newly allocated clusters. This maps to CWE-908 (Use of Uninitialized Resource). Estimated CVSS v3.1 vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N (4.6, Medium). The estimated CISA SSVC vectors are Exploitation: PoC, Technical Impact: Partial.

Severity

4.6 (Medium)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2026-6686"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-908"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-01T15:17:12Z",
    "severity": "MODERATE"
  },
  "details": "FatFs R0.16 and earlier contains an uninitialized cluster exposure when f_lseek() extends files beyond EOF without zero-filling newly allocated clusters. This maps to CWE-908 (Use of Uninitialized Resource). Estimated CVSS v3.1 vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N (4.6, Medium). The estimated CISA SSVC vectors are Exploitation: PoC, Technical Impact: Partial.",
  "id": "GHSA-h94p-vjqx-v7rr",
  "modified": "2026-07-01T15:35:21Z",
  "published": "2026-07-01T15:35:20Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-6686"
    },
    {
      "type": "WEB",
      "url": "https://elm-chan.org/fsw/ff"
    },
    {
      "type": "WEB",
      "url": "https://github.com/runZeroInc/vulns-2026-fatfs-chance"
    },
    {
      "type": "WEB",
      "url": "https://www.runzero.com/advisories/fatfs-uninit-cluster-exposure-cve-2026-6686"
    },
    {
      "type": "WEB",
      "url": "https://www.runzero.com/blog/fatfs-bugs"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-6686 (GCVE-0-2026-6686)

Vulnerability from cvelistv5 – Published: 2026-07-01 13:55 – Updated: 2026-07-01 15:05

Title

FatFs Use of Uninitialized Clusters After Seek Past EOF

Summary

Severity

4.6 (Medium)


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

SSVC

Exploitation: poc Automatable: no Technical Impact: partial

CISA Coordinator (v2.0.3)

CWE

CWE-908 - Use of uninitialized resource

Assigner

runZero

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-uninit-c…	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

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  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-6686",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-07-01T15:05:23.138301Z",
                "version": "2.0.3"
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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.

Action not permitted

GHSA-H94P-VJQX-V7RR

CVE-2026-6686 (GCVE-0-2026-6686)

Tags

Sightings

Nomenclature