CVE-2026-6683 json
FatFs Divide-by-Zero in exFAT Sync
published 2026-07-01 4 mo ago modified 2026-10-25 14 d ago also EUVD-2026-40993
- cvss
- 4.6
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.3%
- EPSS 0.3% chance of exploitation in 30 days, percentile 23%
- public exploits
- 0
- none known
Summary
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.
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- 4 mo ago
Exploit prediction
0.31% chance of exploitation in the next 30 days, higher than 23% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- github.com https://github.com/runZeroInc/vulns-2026-fatfs-chance referenced PoC, tagged "exploit" by a source, unverified
- runzero.com https://www.runzero.com/blog/fatfs-bugs/ referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 4.6 | CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
Affected products
- ChaN FatFs
Classification
- Weakness
-
- CWE-369 Divide By Zero
References
-
github.com
/runZeroInc/vulns-2026-fatfs-chance
technical-description, exploit, third-party-advisory
-
runzero.com
/blog/fatfs-bugs/
third-party-advisory, exploit
-
elm-chan.org
/fsw/ff/
product
-
runzero.com
/advisories/fatfs-exfat-divide-by-zero-cve-2026-6683
third-party-advisory
Sources
- CVE List CVE-2026-6683
- NVD CVE-2026-6683
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