Description
In FatFS R0.16 and earlier contains a FAT32 integer overflow bug in mount_volume() where fasize *= fs->n_fats can wrap, leading to attacker-controlled file-size metadata and unsafe read lengths in downstream callers. This maps to CWE-190 (Integer Overflow or Wraparound). Estimated CVSS v3.1 vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H (7.6, High). Remote delivery is also possible in OTA/update pipelines. The estimated CISA SSVC vectors are Exploitation: PoC, Technical Impact: Total.
Metrics
CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:HWeakness enumeration
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-fat32-int-of-mnt-cve-2026-6682/Third Party Advisory, Exploit
- 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