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CVE-2026-6688

36
FAUCET Score

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.

First published: Jul 1, 2026Last modified: Jul 1, 2026

Impacted Technologies

VendorProductVersion(s)CPE
<= r0.16CPE matchmatch criteria
cpe:2.3:a:elm-chan:fatfs:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.6HIGH

CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Attack Vector
PHYSICAL
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
0.9
Impact Score
6.0
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.43%
Probability of exploitation in next 30 days
EPSS Percentile
35.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0043 is in the 80th percentile among its peer group of 78 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.3 Bluesky, 0.1 Mastodon, and 0.0 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

elm-chan.org / fsw/ff
Product
github.com / runZeroInc/vulns-2026-fatfs-chance
Third Party AdvisoryExploit
runzero.com / advisories/fatfs-long-fn-of-downstream-cve-2026-6688
Third Party Advisory
runzero.com / blog/fatfs-bugs
Third Party AdvisoryExploit