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CVE-2026-6687— FatFs Stack Buffer Overflow via Uncapped exFAT Label Length

CVSS 7.6 · High EPSS 0.46% · P38

Possible ATT&CK Techniques 1AI

T1203 · Exploitation for Client Execution

Affected Version Matrix 1

VendorProductVersion RangeStatus
ChaNFatFs≤ R0.16affected
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I. Basic Information for CVE-2026-6687

Vulnerability Information
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Vulnerability Title
FatFs Stack Buffer Overflow via Uncapped exFAT Label Length
Source: CVE Program / CVE List V5
Vulnerability Description
FatFs R0.16 and earlier contains a stack overflow bug in f_getlabel() because exFAT label length (XDIR_NumLabel) is trusted without enforcing spec maximums. This maps to CWE-121 (Stack-based Buffer Overflow). 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.
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
栈缓冲区溢出
Source: CVE Program / CVE List V5
Vulnerability Title
ChaN FatFs 缓冲区错误漏洞
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及之前版本存在缓冲区错误漏洞，该漏洞源于在f_getlabel()函数中信任exFAT标签长度而未强制实施规范最大值，可能导致栈缓冲区溢出。
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

VendorProductAffected VersionsCPESubscribe
ChaNFatFs 0 ~ R0.16 -

II. Public POCs for CVE-2026-6687

#POC DescriptionSource LinkShenlong Link
AI-Generated POCPremium
Qwen3.6-35B-A3B · 8397 chars
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III. Intelligence Information for CVE-2026-6687

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Vendor Advisories for CVE-2026-6687 (1)

Security Blog Posts for CVE-2026-6687 (1)

Vendor Pages for CVE-2026-6687 (1)

Other References for CVE-2026-6687 (1)

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

CVE-2026-66887.6 HIGHFatFs Buffer Overflow via Unbounded LFN Filename Copy
CVE-2026-66827.6 HIGHFatFs Integer Overflow in FAT32 Volume Mount
CVE-2026-66844.6 MEDIUMFatFs Infinite Loop in GPT Partition Scan
CVE-2026-66864.6 MEDIUMFatFs Use of Uninitialized Clusters After Seek Past EOF
CVE-2026-66834.6 MEDIUMFatFs Divide-by-Zero in exFAT Sync

IV. Related Vulnerabilities

Same product: FatFs
Same vendor: ChaN
Same weakness: CWE-121

V. Comments for CVE-2026-6687

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