Vulnerability 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.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Elm-Chan | Fatfs | < r0.16 |
Related Weaknesses (CWE)
References
- https://elm-chan.org/fsw/ff/Product
- https://github.com/runZeroInc/vulns-2026-fatfs-chanceThird Party AdvisoryExploit
- https://www.runzero.com/advisories/fatfs-gpt-scan-loop-dos-cve-2026-6684/Third Party Advisory
- https://www.runzero.com/blog/fatfs-bugs/Third Party AdvisoryExploit
- https://github.com/runZeroInc/vulns-2026-fatfs-chanceThird Party AdvisoryExploit
FAQ
What is CVE-2026-6684?
CVE-2026-6684 is a vulnerability with a CVSS score of 4.6 (MEDIUM). 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...
How severe is CVE-2026-6684?
CVE-2026-6684 has been rated MEDIUM with a CVSS base score of 4.6/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-6684?
Check the references section above for vendor advisories and patch information. Affected products include: Elm-Chan Fatfs.