CVE-2026-6687
HighCVSS 7.6Exploitation Probability (EPSS)
Low risk11th percentile - higher than 11% of all known CVEs
Summary
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.
Risk Assessment
An attacker with physical access can exploit this vulnerability to execute arbitrary code or cause a denial of service, potentially leading to full system compromise.
Recommendation
Immediately update FatFs to a version later than R0.16 that includes a fix for this bug. If an update is not possible, restrict physical access to systems using this library.
Other vulnerabilities in FatFs
See all- CVE-2026-6688High
A vulnerability in FatFs R0.16 and earlier affects long filename (LFN) handling. The function copies filenames (up to 255 characters) into short fixed buffers without bounds checking, causing buffer overflow.
- CVE-2026-6686Medium
FatFs R0.16 and earlier contains an uninitialized cluster exposure when f_lseek() extends files beyond EOF without zero-filling newly allocated clusters. This can lead to data disclosure.
- CVE-2026-6684Medium
A vulnerability in FatFs prior to R0.16, using GPT scanning with 'FF_LBA64 = 1', causes an infinite loop during filesystem mounting. The issue stems from an unbounded loop count derived from the GPTH_PtNum field in the GPT header, leading to extremely long or infinite mount times.
- CVE-2026-6683Medium
FatFs R0.16 and earlier contains a divide-by-zero bug in exFAT sync logic. Crafted metadata can cause n_fatent - 2 to be zero during write/sync operations, leading to a system crash.
- CVE-2026-6682High
In FatFS R0.16 and earlier, there is an 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.
Original NVD description (English source)
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.