CVE-2026-6688 | FatFs R0.16 and earlier contains a downstream-caller vulnera… | CVSS 7.6 HIGH

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.

Metadata

CVE ID: CVE-2026-6688
State: PUBLISHED
Assigner: runZero
Reserved: 2026-04-20 15:06 UTC
Published: 2026-07-01 14:01 UTC
Last updated: 2026-07-01 15:06 UTC
Primary CWE: CWE-120
CWE-120 Buffer Copy without Checking Size of Input
Vendor / Product: ChaN / FatFs
Sources: cve.org · NVD

Severity & Metrics

7.6 HIGH CVSS 3.1

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

SSVC — CISA Coordinator

Exploitation: PoC
Automatable: no
Tech. Impact: total

Affected products (1)

Vendor	Product	Platform	Versions
ChaN	FatFs	—	0 ≤ R0.16

Weakness (CWE)

CWE	Source	Description
CWE-120	cna	CWE-120 Buffer Copy without Checking Size of Input

CVSS scores (1)

Score	Severity	Version	Source	Vector
7.6	HIGH	3.1	cna	CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

References (4)