Vulnerability Description
FatFs R0.16 and earlier contains a stack overflow bug in f_getlabel() because exFAT label length (XDIR_NumLabel) is trusted without enforcing spec maximums. This maps to CWE-121 (Stack-based Buffer Overflow). 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.
CVSS Score
HIGH
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-exfat-label-len-of-cve-2026-6687/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-2026-6687?
CVE-2026-6687 is a vulnerability with a CVSS score of 7.6 (HIGH). FatFs R0.16 and earlier contains a stack overflow bug in f_getlabel() because exFAT label length (XDIR_NumLabel) is trusted without enforcing spec maximums. This maps to CWE-121 (Stack-based Buffer Ov...
How severe is CVE-2026-6687?
CVE-2026-6687 has been rated HIGH with a CVSS base score of 7.6/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-6687?
Check the references section above for vendor advisories and patch information. Affected products include: Elm-Chan Fatfs.