CVE-2026-6687

EUVD-2026-40999
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.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
7.6 HIGH
PHYSICAL
LOW
NONE
CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Base Score
CVSS 3.x
EPSS Score
Percentile: 37.91%
Affected Products (NVD)
VendorProductVersion
elm-chanfatfs
𝑥
≤ r0.16
𝑥
= Vulnerable software versions
Common Weakness Enumeration
References
https://elm-chan.org/fsw/ff/
https://github.com/runZeroInc/vulns-2026-fatfs-chance
https://www.runzero.com/advisories/fatfs-exfat-label-len-of-cve-2026-6687/
https://www.runzero.com/blog/fatfs-bugs/
https://github.com/runZeroInc/vulns-2026-fatfs-chance