CVE-2026-6683

MediumCVSS 4.6/10Last modified Oct 25, 2026

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.

Metrics

CVSS 3.1 4.6/10CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Weakness enumeration

CWE-369

Affected software

Vendor	Product	Versions
ChaN	FatFs	<= R0.16

References

https://elm-chan.org/fsw/ff/Product
https://github.com/runZeroInc/vulns-2026-fatfs-chanceThird Party Advisory, Exploit
https://www.runzero.com/advisories/fatfs-exfat-divide-by-zero-cve-2026-6683Third Party Advisory
https://www.runzero.com/blog/fatfs-bugs/Third Party Advisory, Exploit
https://github.com/runZeroInc/vulns-2026-fatfs-chanceThird Party Advisory, Exploit

Timeline

Published: Jul 1, 2026
Last modified: Oct 25, 2026
NVD status: Analyzed

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