CVE-2026-6682

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.

CVSS 3.1

7.6CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

EPSS

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

CWE

CWE-190

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-fat32-int-of-mnt-cve-2026-6682/
• https://www.runzero.com/blog/fatfs-bugs/
• https://github.com/runZeroInc/vulns-2026-fatfs-chance

Check your stackJSON