CVE-2026-6688

FatFs R0.16 and earlier contains a downstream-caller vulnerability pattern associated with FatFs long filename handling. With LFN enabled, fno.fname can be up to 255 characters; many callers copy it into short fixed buffers without bounds checks, causing overflow. This maps to CWE-120 Buffer Copy...

CVE-2026-6686

FatFs R0.16 and earlier contains an uninitialized cluster exposure when flseek extends files beyond EOF without zero-filling newly allocated clusters. This maps to CWE-908 Use of Uninitialized Resource. Estimated CVSS v3.1 vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N 4.6, Medium. The...

CVE-2026-6685

FatFs R0.16 and earlier exhibits a stale dirty-cache skip via unsigned-subtraction wrap in fread / fwrite fp-sect - sect cc during interleaved read/write on fragmented filesystems. This maps to CWE-191 Integer Underflow. Estimated CVSS v3.1 vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H 6.1...

CVE-2026-6687

FatFs R0.16 and earlier contains a stack overflow bug in fgetlabel because exFAT label length XDIRNumLabel 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 estimate...

CVE-2026-6682

In FatFS R0.16 and earlier contains a FAT32 integer overflow bug in mountvolume where fasize = fs-nfats 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:...

CVE-2026-6683

FatFs R0.16 and earlier contains a divide-by-zero in exFAT sync logic bug when crafted metadata causes nfatent - 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...

EUVD-2026-40999

FatFs R0.16 and earlier contains a stack overflow bug in fgetlabel because exFAT label length XDIRNumLabel 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 estimate...

EUVD-2026-40998

FatFs R0.16 and earlier contains an uninitialized cluster exposure when flseek extends files beyond EOF without zero-filling newly allocated clusters. This maps to CWE-908 Use of Uninitialized Resource. Estimated CVSS v3.1 vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N 4.6, Medium. The...

EUVD-2026-40996

FatFs R0.16 and earlier exhibits a stale dirty-cache skip via unsigned-subtraction wrap in fread / fwrite fp-sect - sect cc during interleaved read/write on fragmented filesystems. This maps to CWE-191 Integer Underflow. Estimated CVSS v3.1 vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H 6.1...