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CVE-2026-6683

FatFs Divide-by-Zero in exFAT Sync

Published: Jul 1, 2026Updated: Jul 2, 2026 Sources: CVE List NVDCWE-369
4.6MEDIUM
NVD MITRE
EPSS Score
0.2%
Top 89.4%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
No Fix Available
Self-Check
Not available

Description

FatFs R0.16 and earlier contains a divide-by-zero in exFAT sync logic bug when crafted metadata causes n_fatent - 2 to be zero during write/sync operations. This maps to CWE-369 (Divide By Zero). Estimated CVSS v3.1 vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H (4.6, Medium). Network-delivered update media can make this remote in some pipelines. The estimated CISA SSVC vectors are Exploitation: PoC, Technical Impact: Partial.

No summary for this CVE yet.

CVSS Vector Breakdown

AV:PAC:LPR:NUI:NS:UC:NI:NA:H
Exploitability
AV:PAttack Vector
Physical
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:NIntegrity
None
A:HAvailability
High
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Weaknesses

CWE-369

Affected Products

elm-chan
fatfs
ChaN
FatFs

Exploitability

No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.

References

https://elm-chan.org/fsw/ff/
elm-chan.org
https://github.com/runZeroInc/vulns-2026-fatfs-chance
github.com
https://www.runzero.com/advisories/fatfs-exfat-divide-by-zero-cve-2026-6683
runzero.com
and 1 more references View all →
News mentions
1

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