CVE-2026-6687 FatFs Stack Buffer Overflow via Uncapped exFAT Label Length
Attackers can trigger a stack buffer overflow in FatFs by providing a malicious exFAT label, potentially leading to code execution or system crashes.
- 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-2026-6687?
CVE-2026-6687 is a high-severity memory corruption 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 R0.16 and earlier contains a stack overflow bug in f_getlabel() because exFAT label length (XDIR_NumLabel) is trusted without enforcing spec maximums. This maps to CWE-121 (Stack-based Buffer Overflow). 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). The estimated CISA SSVC vectors are Exploitation: PoC, Technical Impact: Total.
Weakness: CWE-121
Which versions are affected by CVE-2026-6687?
It affects 1 product.
Products include Elm-Chan Fatfs.
How do I fix CVE-2026-6687?
No fix has been published for CVE-2026-6687 yet. Limit exposure of the affected software until one is available.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-6687 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-6687 exists.
Other vulnerabilities in ChaN FatFs
- CVE-2026-6682 FatFs Integer Overflow in FAT32 Volume Mount
- 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-wghw-hg6m-7rh3.