Vulnerability in Chan Fatfs
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.
EPSS: 0.004 (35.2th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 4.6 (Medium). Vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
Affected products
- Chan Fatfs — versions 0
- Elm-chan Fatfs
Weakness classification (CWE)
References
- 44488dab-36db-4358-99f9-bc116477f914 (Exploit, Third Party Advisory, third-party-advisory)
- 44488dab-36db-4358-99f9-bc116477f914 (Exploit, technical-description, Third Party Advisory)
- 44488dab-36db-4358-99f9-bc116477f914 (Product, product)
- 44488dab-36db-4358-99f9-bc116477f914 (Third Party Advisory, third-party-advisory)
Frequently asked questions
- What is CVE-2026-6683?
- CVE-2026-6683 is a medium-severity vulnerability in Chan Fatfs, classified under Divide By Zero. CVSS score: 4.6/10. Published 2026-07-01.
- How severe is CVE-2026-6683?
- Medium severity. CVSS v3 base score is 4.6 out of 10.