CVE-2026-6684Public exploit

Mount-time hang via unbounded GPT partition scan

Published Jul 1, 2026 · Updated Jul 1, 2026

Loop denial of service in ChaN FatFs before R0.16 allows physically proximate attackers to hang mounts with a crafted GPT image. The GPT scan reads GPTH_PtNum from the on-disk header and uses it directly as the partition-entry loop bound without a cap. The path is reachable only when FF_LBA64 = 1; a malicious storage device can stall boot or service startup until the medium is removed or the device is recovered.

CVSS severity4.6
Medium
EPSS probability0.31%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Loop denial of service in ChaN FatFs before R0.16 allows physically proximate attackers to hang mounts with a crafted GPT image. The GPT scan reads GPTH_PtNum from the on-disk header and uses it directly as the partition-entry loop bound without a cap. The path is reachable only when FF_LBA64 = 1; a malicious storage device can stall boot or service startup until the medium is removed or the device is recovered.

The record

CVE
CVE-2026-6684
Published
Jul 1, 2026
Updated
Jul 1, 2026
Vendor
ChaN
Product
FatFs
Classifications
CWE-835, T1499
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

4.6runZeroCVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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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-835Loop with Unreachable Exit Condition ('Infinite Loop')
T1499Endpoint Denial of Service

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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