CVE-2026-6688

HIGH LAB

FatFs Buffer Overflow via Unbounded LFN Filename Copy

Title source: cna
STIX 2.1

Description

FatFs R0.16 and earlier contains a downstream-caller vulnerability pattern associated with FatFs long filename handling. With LFN enabled, fno.fname can be up to 255 characters; many callers copy it into short fixed buffers without bounds checks, causing overflow. This maps to CWE-120 (Buffer Copy without Checking Size of Input). 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). 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/

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

COMMUNITY
Community Lab
docker pull espressif/idf:v5.3.2

Details

CWE
CWE-120
Status published
Products (2)
ChaN/FatFs < R0.16
elm-chan/fatfs < r0.16
Published Jul 01, 2026
Tracked Since Jul 01, 2026