CVE-2026-6688: high-severity vulnerability in ChaN FatFs
FatFs Buffer Overflow via Unbounded LFN Filename Copy
Published
E-mail alert when it lands in KEV, gets a public PoC or its score goes up.
21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 7.6epss 0.3%
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 without Checking Size of Input). 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.
CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Affected products
ChaN · FatFsRelated CVEs — ChaN FatFs
In the same product, most dangerous first.
CVE-2026-6687HIGHFatFs Stack Buffer Overflow via Uncapped exFAT Label LengthEPSS 0.3%CVE-2026-6682HIGHFatFs Integer Overflow in FAT32 Volume MountEPSS 0.3%CVE-2026-6684MEDIUMFatFs Infinite Loop in GPT Partition ScanEPSS 0.3%CVE-2026-6683MEDIUMFatFs Divide-by-Zero in exFAT SyncEPSS 0.3%CVE-2026-6686MEDIUMFatFs Use of Uninitialized Clusters After Seek Past EOFEPSS 0.3%