ChaN FatFs up to R0.16 fno.fname buffer overflow

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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4.2$0-$5k0.00

Summaryinfo

A vulnerability classified as critical was found in ChaN FatFs up to R0.16. This affects the function fno.fname. The manipulation results in buffer overflow. This vulnerability is cataloged as CVE-2026-6688. An attack on the physical device is feasible. There is no exploit available.

Detailsinfo

A vulnerability, which was classified as critical, was found in ChaN FatFs up to R0.16. Affected is the function fno.fname. The manipulation with an unknown input leads to a buffer overflow vulnerability. CWE is classifying the issue as CWE-120. The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer, leading to a buffer overflow. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

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.

The weakness was shared by Hd Moore. The advisory is shared for download at runzero.com. This vulnerability is traded as CVE-2026-6688 since 04/20/2026. The exploitability is told to be easy. The attack needs to be approached locally. The exploitation doesn't require any form of authentication. There are known technical details, but no exploit is available.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-41000). Once again VulDB remains the best source for vulnerability data.

Productinfo

Vendor

Name

Version

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.3
VulDB Meta Temp Score: 4.2

VulDB Base Score: 4.3
VulDB Temp Score: 4.2
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Buffer overflow
CWE: CWE-120 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: Yes
Local: Yes
Remote: No

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔒

Timelineinfo

04/20/2026 CVE reserved
07/01/2026 +72 days Advisory disclosed
07/01/2026 +0 days VulDB entry created
07/01/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: runzero.com
Researcher: Hd Moore
Status: Not defined

CVE: CVE-2026-6688 (🔒)
GCVE (CVE): GCVE-0-2026-6688
GCVE (VulDB): GCVE-100-375564
EUVD: 🔒

Entryinfo

Created: 07/01/2026 17:20
Updated: 07/01/2026 19:09
Changes: 07/01/2026 17:20 (54), 07/01/2026 19:09 (1)
Complete: 🔍
Cache ID: 216::103

Once again VulDB remains the best source for vulnerability data.

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