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CVE-2026-6682— FatFs Integer Overflow in FAT32 Volume Mount

Quick assessment

Affected
ChaN FatFs
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

ChaN FatFs是ChaN公司的一个为嵌入式系统设计的通用 FAT/exFAT 文件系统模块。 ChaN FatFs R0.16及之前版本存在数字错误漏洞，该漏洞源于mount_volume()函数中存在FAT32整数溢出错误，导致fasize *= fs->n_fats可能发生环绕，从而允许攻击者控制文件大小元数据，并在下游调用者中造成不安全的读取长度。

CVSS 7.6 · High EPSS 0.32% · P23

Affected Version Matrix 1

VendorProduct Version RangeStatus
ChaN FatFs ≤ R0.16 affected
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I. Basic Information for CVE-2026-6682

Vulnerability Information
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Vulnerability Title
FatFs Integer Overflow in FAT32 Volume Mount
Source: CVE Program / CVE List V5
Vulnerability Description
In FatFS R0.16 and earlier contains a FAT32 integer overflow bug in mount_volume() where fasize *= fs->n_fats 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: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H (7.6, High). Remote delivery is also possible in OTA/update pipelines. The estimated CISA SSVC vectors are Exploitation: PoC, Technical Impact: Total.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
整数溢出或超界折返
Source: CVE Program / CVE List V5
Vulnerability Title
ChaN FatFs 数字错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
ChaN FatFs是ChaN公司的一个为嵌入式系统设计的通用 FAT/exFAT 文件系统模块。 ChaN FatFs R0.16及之前版本存在数字错误漏洞，该漏洞源于mount_volume()函数中存在FAT32整数溢出错误，导致fasize *= fs->n_fats可能发生环绕，从而允许攻击者控制文件大小元数据，并在下游调用者中造成不安全的读取长度。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
ChaN FatFs 0 ~ R0.16 -

II. Public POCs for CVE-2026-6682

# POC Description Source Link Shenlong Link
AI-Generated POC Premium
Qwen3.6-35B-A3B · 9099 chars
Pro+ exclusive includes:
Vulnerability reproduction recording (real sandbox build + trigger, exclusive)
In-depth vulnerability mechanism
Trigger conditions & impact
Full executable POC code
Exploit chain & mitigation
POC zip download
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III. Intelligence Information for CVE-2026-6682

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Vendor Advisories for CVE-2026-6682 (1)

Security Blog Posts for CVE-2026-6682 (1)

Vendor Pages for CVE-2026-6682 (1)

Other References for CVE-2026-6682 (1)

Same Patch Batch · ChaN · 2026-07-01 · 6 CVEs total

CVE-2026-6688 7.6 HIGH FatFs Buffer Overflow via Unbounded LFN Filename Copy
CVE-2026-6687 7.6 HIGH FatFs Stack Buffer Overflow via Uncapped exFAT Label Length
CVE-2026-6684 4.6 MEDIUM FatFs Infinite Loop in GPT Partition Scan
CVE-2026-6686 4.6 MEDIUM FatFs Use of Uninitialized Clusters After Seek Past EOF
CVE-2026-6683 4.6 MEDIUM FatFs Divide-by-Zero in exFAT Sync

IV. Related Vulnerabilities

Same product: FatFs
Same vendor: ChaN
Same weakness: CWE-190

V. Comments for CVE-2026-6682

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