VDB-375559 · CVE-2026-6684 · GCVE-0-2026-6684

ChaN FatFs up to R0.15 Header Field infinite loop

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
2.3	$0-$5k	0.66

Summaryinfo

A vulnerability identified as problematic has been detected in ChaN FatFs up to R0.15. This affects an unknown function of the component Header Field Handler. This manipulation causes infinite loop. The identification of this vulnerability is CVE-2026-6684. It is feasible to perform the attack on the physical device. There is no exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in ChaN FatFs up to R0.15. It has been declared as problematic. Affected by this vulnerability is some unknown functionality of the component Header Field Handler. The manipulation with an unknown input leads to a infinite loop vulnerability. The CWE definition for the vulnerability is CWE-835. The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop. As an impact it is known to affect availability. The summary by CVE is:

FatFs prior to R0.16 that use GPT scanning with 'FF_LBA64 = 1' contains an issue where an unbounded loop count derived from GPT header field GPTH_PtNum, enabling extremely long or effectively infinite mount-time scans. This maps to CWE-835 (Loop with Unreachable Exit Condition). 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). The estimated CISA SSVC vectors are Exploitation: PoC, Technical Impact: Partial.

The weakness was shared by Hd Moore. It is possible to read the advisory at runzero.com. This vulnerability is known as CVE-2026-6684 since 04/20/2026. The exploitation appears to be easy. Attacking locally is a requirement. The exploitation doesn't need any form of authentication. The technical details are unknown and an exploit is not publicly available.

Upgrading to version R0.16 eliminates this vulnerability.

Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Vendor

ChaN

Name

FatFs

Version

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 2.4
VulDB Meta Temp Score: 2.3

VulDB Base Score: 2.4
VulDB Temp Score: 2.3
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Infinite loop
CWE: CWE-835 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: Yes
Local: Yes
Remote: No

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

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: FatFs R0.16

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: Confirmed

CVE: CVE-2026-6684 (🔒)
GCVE (CVE): GCVE-0-2026-6684
GCVE (VulDB): GCVE-100-375559

Entryinfo

Created: 07/01/2026 17:14
Changes: 07/01/2026 17:14 (56)
Complete: 🔍
Cache ID: 216::103