CVE-2026-6682 FatFs Integer Overflow in FAT32 Volume Mount
An integer overflow in FatFs allows attackers to trigger unsafe memory operations via crafted FAT32 volumes, potentially leading to code execution or denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-6682?
CVE-2026-6682 is a high-severity vulnerability in ChaN FatFs, published on 1 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In FatFS R0.16 and earlier contains a FAT32 integer overflow bug in mount_volume() where fasize *= fs->n_fats can wrap, leading to attacker-controlled file-size metadata and unsafe read lengths in downstream callers. This maps to CWE-190 (Integer Overflow or Wraparound). 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). Remote delivery is also possible in OTA/update pipelines. The estimated CISA SSVC vectors are Exploitation: PoC, Technical Impact: Total.
Weakness: CWE-190
Which versions are affected by CVE-2026-6682?
It affects 1 product.
Products include Elm-Chan Fatfs.
How do I fix CVE-2026-6682?
No fix has been published for CVE-2026-6682 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-6682 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-6682 exists.
Other vulnerabilities in ChaN FatFs
- CVE-2026-6687 FatFs Stack Buffer Overflow via Uncapped exFAT Label Length
- CVE-2026-6688 FatFs Buffer Overflow via Unbounded LFN Filename Copy
- CVE-2026-6683 FatFs Divide-by-Zero in exFAT Sync
- CVE-2026-6684 FatFs Infinite Loop in GPT Partition Scan
- CVE-2026-6686 FatFs Use of Uninitialized Clusters After Seek Past EOF
Sources
Also known as GHSA-c25x-vcg6-4ccx.