CVE-2026-6683

medium

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.

References

https://www.runzero.com/advisories/fatfs-exfat-divide-by-zero-cve-2026-6683

https://thehackernews.com/2026/07/unpatched-flaws-disclosed-in-filesystem.html

https://www.runzero.com/blog/fatfs-bugs/

https://github.com/runZeroInc/vulns-2026-fatfs-chance

https://elm-chan.org/fsw/ff/

Details

Source: Mitre, NVD

Published: 2026-07-01

Updated: 2026-07-02

Risk Information

CVSS v2

Base Score: 4.9

Vector: CVSS2#AV:L/AC:L/Au:N/C:N/I:N/A:C

Severity: Medium

CVSS v3

Base Score: 4.6

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

Severity: Medium

EPSS

EPSS: 0.00185