CVE-2026-6687: Elm-Chan Fatfs

High severity, CVSS 7.6. EPSS: 0.3% chance of exploitation in the next 30 days.

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.

Affected products

• Elm-Chan Fatfs: up to and including r0.16

Published 2026-07-01. Last modified 2026-07-02.