CVE-2026-6687Public exploit

Memory corruption via uncapped exFAT label length

Published Jul 1, 2026 · Updated Jul 1, 2026

Stack-based buffer overflow in ChaN FatFs R0.16 and earlier allows physically proximate attackers to corrupt memory via crafted exFAT media. The f_getlabel() loop uses the on-disk XDIR_NumLabel byte as its copy bound instead of enforcing the 11-character exFAT limit, overrunning a caller-supplied stack buffer. Exploitation requires a controlled exFAT volume and an application call to f_getlabel(); resulting memory corruption can crash firmware or alter control flow.

CVSS severity7.6
High
EPSS probability0.35%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack-based buffer overflow in ChaN FatFs R0.16 and earlier allows physically proximate attackers to corrupt memory via crafted exFAT media. The f_getlabel() loop uses the on-disk XDIR_NumLabel byte as its copy bound instead of enforcing the 11-character exFAT limit, overrunning a caller-supplied stack buffer. Exploitation requires a controlled exFAT volume and an application call to f_getlabel(); resulting memory corruption can crash firmware or alter control flow.

The record

CVE
CVE-2026-6687
Published
Jul 1, 2026
Updated
Jul 1, 2026
Vendor
ChaN
Product
FatFs
Classifications
CWE-121
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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorphysical
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-121Stack-based Buffer Overflow

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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