CVE-2026-6684 — Security Box Score

CVE · referencelatest edition

Reference page — cumulative record through Wednesday, August 19, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2026-6684MEDIUM

ChaN FatFs — FatFs Infinite Loop in GPT Partition Scan

  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   P   L   N   N  U  N  N  H    4.6   .0043   36.0     —

AFFECTED
  Product  Versions     Fixed
  FatFs    unspecified  —

TIMELINE
  Apr 20  Reserved by runZero
  Jul 1   EXPLOIT PUBLISHED — CVE-2026-6684 (ChaN FatFs). Public exploit reference added.
  Jul 1   Published (CNA: runZero)

CWE-835 · CNA: runZero · CVSS v3.1 · 4 references · NVD status: Analyzed

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.

Lifecycle

Complete event history — 3 events, chronological
Date	Event	Detail
April 20, 2026	Reserved	Reserved by runZero
July 1, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2026-6684 (ChaN FatFs). Public exploit reference added.
July 1, 2026	Published	Published (CNA: runZero)

Affected

Affected products and packages — 1 row
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
ChaN	FatFs	—	—	—

Weaknesses

CWE-835

References (4)

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-gpt-scan-loop-dos-cve-2026-6684/ [Third Party Advisory]
https://www.runzero.com/blog/fatfs-bugs/ [Third Party Advisory, Exploit]

Authoritative record: CVE-2026-6684 at cve.org

Vendors: chan

Weaknesses: CWE-835

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-6684 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Wednesday, August 19, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.