CVE-2026-6684

medium

Description

FatFs prior to R0.16 that use GPT scanning with 'FF_LBA64 = 1' contains an issue where an unbounded loop count derived from GPT header field GPTH_PtNum, enabling extremely long or effectively infinite mount-time scans. This maps to CWE-835 (Loop with Unreachable Exit Condition). Estimated CVSS v3.1 vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H (4.6, Medium). The estimated CISA SSVC vectors are Exploitation: PoC, Technical Impact: Partial.

References

https://www.runzero.com/blog/fatfs-bugs/

https://www.runzero.com/advisories/fatfs-gpt-scan-loop-dos-cve-2026-6684/

https://github.com/runZeroInc/vulns-2026-fatfs-chance

https://elm-chan.org/fsw/ff/

Details

Source: Mitre, NVD

Published: 2026-07-01

Updated: 2026-07-01

Risk Information

CVSS v2

Base Score: 4.9

Vector: CVSS2#AV:L/AC:L/Au:N/C:N/I:N/A:C

Severity: Medium

CVSS v3

Base Score: 4.6

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

Severity: Medium