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.
References
| Link | Resource |
|---|---|
| https://elm-chan.org/fsw/ff/ | Product |
| https://github.com/runZeroInc/vulns-2026-fatfs-chance | Third Party Advisory Exploit |
| https://www.runzero.com/advisories/fatfs-long-fn-of-downstream-cve-2026-6688/ | Third Party Advisory |
| https://www.runzero.com/blog/fatfs-bugs/ | Third Party Advisory Exploit |
| https://github.com/runZeroInc/vulns-2026-fatfs-chance | Third Party Advisory Exploit |
Configurations
History
02 Jul 2026, 14:38
| Type | Values Removed | Values Added |
|---|---|---|
| CPE | cpe:2.3:a:elm-chan:fatfs:*:*:*:*:*:*:*:* | |
| First Time |
Elm-chan
Elm-chan fatfs |
|
| References | () https://elm-chan.org/fsw/ff/ - Product | |
| References | () https://github.com/runZeroInc/vulns-2026-fatfs-chance - Third Party Advisory, Exploit | |
| References | () https://www.runzero.com/advisories/fatfs-long-fn-of-downstream-cve-2026-6688/ - Third Party Advisory | |
| References | () https://www.runzero.com/blog/fatfs-bugs/ - Third Party Advisory, Exploit |
01 Jul 2026, 16:16
| Type | Values Removed | Values Added |
|---|---|---|
| References | () https://github.com/runZeroInc/vulns-2026-fatfs-chance - |
01 Jul 2026, 15:17
| Type | Values Removed | Values Added |
|---|---|---|
| New CVE |
Information
Published : 2026-07-01 15:17
Updated : 2026-07-02 14:38
NVD link : CVE-2026-6688
Mitre link : CVE-2026-6688
CVE.ORG link : CVE-2026-6688
JSON object : View
Products Affected
elm-chan
- fatfs
CWE
CWE-120
Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')