CVEvulnerability
CVE-2026-6686
4.6 MEDIUM
Official page ↗
- Status
- Analyzed
- Published
- 2026-07-01
- Last modified
- 2026-10-25
- Assigner
- 44488dab-36db-4358-99f9-bc116477f914
- CVSS 3.1 (44488dab-36db-4358-99f9-bc116477f914)
- 4.6 MEDIUM — CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
- Weaknesses
- CWE-908
Description
FatFs R0.16 and earlier contains an uninitialized cluster exposure when f_lseek() extends files beyond EOF without zero-filling newly allocated clusters. This maps to CWE-908 (Use of Uninitialized Resource). Estimated CVSS v3.1 vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N (4.6, Medium). The estimated CISA SSVC vectors are Exploitation: PoC, Technical Impact: Partial.
Affected configurations
• elm-chan fatfs (<= r0.16)
Related
Weakness · CWE (1)
- CWE-908 Use of Uninitialized Resource weakness
References
- 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-uninit-cluster-exposure-cve-2026-6686/ 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