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

Vulnerability from cvelistv5 – Published: 2026-07-01 13:55 – Updated: 2026-07-01 15:05
VLAI
Title
FatFs Use of Uninitialized Clusters After Seek Past EOF
Summary
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
SSVC
Exploitation: poc Automatable: no Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
  • CWE-908 - Use of uninitialized resource
Assigner
References
Impacted products
Vendor Product Version
ChaN FatFs Affected: 0 , ≤ R0.16 (custom)
Create a notification for this product.
Date Public
2026-07-01 13:00
Credits
HD Moore of runZero, Inc. Tod Beardsley of runZero, Inc.
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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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.