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.
References (4)
Core 4
Core References
Third Party Advisory third-party-advisory
https://www.runzero.com/blog/fatfs-bugs/
Technical Description technical-description
https://github.com/runZeroInc/vulns-2026-fatfs-chance
Product product
https://elm-chan.org/fsw/ff/
Third Party Advisory third-party-advisory
https://www.runzero.com/advisories/fatfs-fat32-int-of-mnt-cve-2026-6682/
Scores
CVSS v3
7.6
EPSS
0.0043
EPSS Percentile
35.2%
Attack Vector
PHYSICAL
CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
CISA SSVC
Vulnrichment
Exploitation
poc
Automatable
no
Technical Impact
total
Lab Environment
Details
CWE
CWE-190
Status
published
Products (2)
ChaN/FatFs
< R0.16
elm-chan/fatfs
< r0.16
Published
Jul 01, 2026
Tracked Since
Jul 01, 2026