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VulnerabilityPublished

CVE-2026-6687: ChaN FatFs · Stack-based Buffer Overflow

Affects ChaN FatFsSource CVE Database V5

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Not known to be exploited · CVSS 7.6 High.

Data as of 13 Nov 2026, 23:54 UTC

CVSS 3.1 base score
7.6High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.3% chance of exploitation in 30 days – higher than 28% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 1 Jul 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 13 Nov 2026.

What to do

Affected software

ProductAffectedFixed in
ChaNFatFsAffected
  • =0
Fixed in–

AI-suggested

Until an official fix is available, avoid processing untrusted exFAT volumes with FatFs R0.16 or earlier. Monitor vendor channels for updates and apply patches promptly once released.

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.

References

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