CVE-2026-6687

HIGH LAB

FatFs Stack Buffer Overflow via Uncapped exFAT Label Length

Title source: cna
STIX 2.1

Description

FatFs R0.16 and earlier contains a stack overflow bug in f_getlabel() because exFAT label length (XDIR_NumLabel) is trusted without enforcing spec maximums. This maps to CWE-121 (Stack-based Buffer Overflow). 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 0.0046
EPSS Percentile 37.5%
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-121
Status published
Products (2)
ChaN/FatFs < R0.16
elm-chan/fatfs < r0.16
Published Jul 01, 2026
Tracked Since Jul 01, 2026