CVE-2026-6684 FatFs Infinite Loop in GPT Partition Scan
An attacker with physical access can cause a denial of service via an infinite loop during GPT partition scanning in FatFs when 64-bit LBA support is enabled.
- 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-2026-6684?
CVE-2026-6684 is a medium-severity denial of service 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
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.
Weakness: CWE-835
Which versions are affected by CVE-2026-6684?
It affects 1 product.
Products include Elm-Chan Fatfs.
How do I fix CVE-2026-6684?
No fix has been published for CVE-2026-6684 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-6684 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-6684 exists.
Other vulnerabilities in ChaN FatFs
- CVE-2026-6682 FatFs Integer Overflow in FAT32 Volume Mount
- 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-2026-6686 FatFs Use of Uninitialized Clusters After Seek Past EOF
Sources
Also known as GHSA-vhc7-qgwj-vx6v.