CVE-2026-6682Public exploit

Memory corruption via wrapped FAT size calculation

Published Jul 1, 2026 · Updated Jul 1, 2026

Integer overflow in FatFs R0.16 and earlier allows attackers to corrupt memory via a crafted FAT32 volume mounted by an embedded device. In mount_volume(), the 32-bit fasize multiplication by the FAT-copy count wraps, placing the data region inside attacker-controlled FAT space and allowing forged file sizes to drive oversized f_read calls. Exploitation requires control of mounted media or an unverified OTA image and a downstream caller that trusts the forged size; successful exploitation crashes the device or executes code.

CVSS severity7.6
High
EPSS probability0.32%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Integer overflow in FatFs R0.16 and earlier allows attackers to corrupt memory via a crafted FAT32 volume mounted by an embedded device. In mount_volume(), the 32-bit fasize multiplication by the FAT-copy count wraps, placing the data region inside attacker-controlled FAT space and allowing forged file sizes to drive oversized f_read calls. Exploitation requires control of mounted media or an unverified OTA image and a downstream caller that trusts the forged size; successful exploitation crashes the device or executes code.

The record

CVE
CVE-2026-6682
Published
Jul 1, 2026
Updated
Jul 1, 2026
Vendor
ChaN
Product
FatFs
Classifications
CWE-190, T1200
Attack vector
physical
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 1, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 1, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <=R0.16

What conditions does exploitation require?

Attack vectorphysical
Required privilegesunauthenticated

What is affected?

ChaN · FatFsversion=0 <=R0.16

Published CVSS scores

7.6runZeroCVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorphysical
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-190Integer Overflow or Wraparound
T1200Hardware Additions

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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