CVE-2026-6685
6.1
CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
Summary
FatFs R0.16 and earlier exhibits a stale dirty-cache skip via unsigned-subtraction wrap in f_read() / f_write() (fp->sect - sect < cc) during interleaved read/write on fragmented filesystems. This maps to CWE-191 (Integer Underflow). Estimated CVSS v3.1 vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H (6.1, Medium). The estimated CISA SSVC vectors are Exploitation: PoC, Technical Impact: Total.
Affected Software
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| ChaN | FatFs | 0 <= R0.16 | affected |
Weaknesses
- CWE-191: CWE-191 Integer underflow (wrap or wraparound)
ADP Enrichment
CISA ADP Vulnrichment
- SSVC:
- Exploitation: poc
- Automatable: no
- Technical Impact: partial
Additional References
References
- https://www.runzero.com/blog/fatfs-bugs/
- https://github.com/runZeroInc/vulns-2026-fatfs-chance
- https://elm-chan.org/fsw/ff/
- https://www.runzero.com/advisories/fatfs-unsigned-sub-wrap-cve-2026-6685/
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