CVE-2026-6683Disclosure(elm-chan / fatfs)

LOWCVSS 4.6 · MEDIUM

Exploit discussion active in current signal (1 latest mentions)

Immediate actions

Patch elm-chan fatfs systems immediately
Hunt for exploitation attempts and persistence artifacts
Increase monitoring for publicly documented tradecraft

Recommended action window: High priority (within 72h)

NVD description

FatFs R0.16 and earlier contains a divide-by-zero in exFAT sync logic bug when crafted metadata causes n_fatent - 2 to be zero during write/sync operations. This maps to CWE-369 (Divide By Zero). 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). Network-delivered update media can make this remote in some pipelines. The estimated CISA SSVC vectors are Exploitation: PoC, Technical Impact: Partial.

elm-chan CVEs Back to dashboard

2.0/ 10 priority

Sources & remediation

Exploit / PoC references

Vendor / third-party advisories

https://www.runzero.com/advisories/fatfs-exfat-divide-by-zero-cve-2026-6683

Other references

https://elm-chan.org/fsw/ff/

Weakness type (CWE)

CWE-369

Priority

LOW

Exploitation

NONE

PoC

YES

Patch

AVAILABLE

Momentum

STABLE

Are you affected?

If you run products in this scope, you should treat this CVE as relevant to your environment.

fatfs

Threat summary

Public PoC is present in monitored signal
Patch or workaround signal is available
2 mentions across 2 observed days
Momentum state: stable

What's happening

PoC mentioned or linked in 1 signal
Patch or workaround mentioned in 1 signal
Technical details provided in 1 signal
Disclosure: 1 classified signal
General: 1 classified signal
Peaked 1d ago at 1 mentions (2026-07-04); latest day: 1
2 total mentions across 2 days

Affected systems

Vendors

elm-chan

Products

fatfs

Deep dive

Activity timeline2 mentions / 2d

Signal classification2 categories

Disclosure

150.0%

General

150.0%

Classification over time

Date	Total	Labels

2026-07-04	1	Disclosure1
2026-07-06	1	General1

Full discourse2 posts

Rıdvan Yağlı@ridvanyagli91d
Disclosure
🚨 Siber güvenlik şirketi runZero tarafından, yaygın olarak kullanılan FatFs dosya sistemi kütüphanesinde 7 güvenlik açığı tespit edildi. Güvenlik kameraları, IoT cihazları, dronlar ve birçok gömülü sistem potansiyel olarak etkilenebilir. En kritik açık CVE-2026-6682 (CVSS 7.6), özel hazırlanmış FAT32/exFAT medya üzerinden bellek bozulmasına (memory corruption) ve bazı senaryolarda uzaktan kod çalıştırmaya (RCE) yol açabiliyor. Tespit edilen CVE'ler: • CVE-2026-6682 – Integer overflow → Memory corruption / RCE • CVE-2026-6683 – exFAT divide-by-zero (DoS) • CVE-2026-6684 – Bozuk GPT partition tablosu ile DoS • CVE-2026-6685 – Cache hesaplama hatası, veri bozulması • CVE-2026-6686 – Bilgi sızıntısı • CVE-2026-6687 – exFAT volume label buffer overflow • CVE-2026-6688 – Long File Name (LFN) buffer overflow Şu ana kadar aktif istismar raporlanmadı. Ancak PoC'ler genele açık durumda. FAT/FAT32/exFAT kullanan gömülü sistem geliştiren üreticilerin FatFs entegrasyonlarını gözden geçirerek gerekli güvenlik güncellemelerini yayınlaması önem taşıyor.
Post summary
RunZero has disclosed seven CVEs in FatFs, including a critical RCE and several DoS flaws; PoCs are publicly available but no active exploitation has been reported, prompting vendors to release updates.
01072828
2.2K followersView on X
Philips_NE555@Philips_NE55589d
General
CVE-2026-6685 CVE-2026-6683 I couldn't find the condition to trigger these bugs but it might lead the system crash.
Post summary
The text merely lists CVE identifiers and expresses uncertainty about triggering them, providing no substantive technical or operational details.
10000114
2.4K followersView on X

CPE platform detail1 entries

Part:

Vendor:

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Version:

Target SW:

Target HW:

1 of 1 entries

Part	Vendor	Product	Version	Target SW	Target HW
App	elm-chan	fatfs	-	-	-

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