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CVE-2026-6686

Estado: AnalizadaMedia (4.6)—

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.

CVSS

Probabilidad de explotación (EPSS)

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

Tecnologías afectadas (1)

Elm-chan — Fatfs

CWE

Referencias

JSON original (NVD)

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{
  "id": "CVE-2026-6686",
  "cveTags": [],
  "metrics": {
    "ssvcV203": [
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        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-6686",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2026-07-01T15:05:23.138301Z"
        }
      }
    ],
    "cvssMetricV31": [
      {
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        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 4.6,
          "attackVector": "PHYSICAL",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "NONE",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "HIGH"
        },
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      "affectedData": [
        {
          "vendor": "ChaN",
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  "published": "2026-07-01T15:17:12.763",
  "references": [
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      "url": "https://elm-chan.org/fsw/ff/",
      "tags": [
        "Product"
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      "source": "44488dab-36db-4358-99f9-bc116477f914"
    },
    {
      "url": "https://github.com/runZeroInc/vulns-2026-fatfs-chance",
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    },
    {
      "url": "https://www.runzero.com/advisories/fatfs-uninit-cluster-exposure-cve-2026-6686/",
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      "tags": [
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      "source": "44488dab-36db-4358-99f9-bc116477f914"
    },
    {
      "url": "https://github.com/runZeroInc/vulns-2026-fatfs-chance",
      "tags": [
        "Third Party Advisory",
        "Exploit"
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      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"
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  ],
  "vulnStatus": "Analyzed",
  "weaknesses": [
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      "description": [
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  "descriptions": [
    {
      "lang": "en",
      "value": "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."
    }
  ],
  "lastModified": "2026-07-02T14:38:35.823",
  "configurations": [
    {
      "nodes": [
        {
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              "versionEndIncluding": "r0.16"
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}