CVE-2026-6683

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.

CVSS 3.1

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

EPSS

0.3% chance of exploitation in the next 30 days; higher than 23% of CVEs (scores of 2026-10-25)

CWE

CWE-369

Published

2026-07-01

Modified

2026-10-25

Record from

the NVD, synced 2026-10-25

Affected

• elm-chan:fatfs

References

• https://elm-chan.org/fsw/ff/
• https://github.com/runZeroInc/vulns-2026-fatfs-chance
• https://www.runzero.com/advisories/fatfs-exfat-divide-by-zero-cve-2026-6683
• https://www.runzero.com/blog/fatfs-bugs/
• https://github.com/runZeroInc/vulns-2026-fatfs-chance

Check your stackJSON