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VulnerabilityPublished

CVE-2026-6684: ChaN FatFs · Infinite Loop

Affects ChaN FatFsSource CVE Database V5

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Not known to be exploited · CVSS 4.6 Medium : upgrade to R0.16 when convenient.

Data as of 13 Nov 2026, 23:54 UTC

CVSS 3.1 base score
4.6Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.3% chance of exploitation in 30 days – higher than 23% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in R0.16
CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/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

Upgrade ChaN FatFs to R0.16.

Affected software

ProductAffectedFixed in
ChaNFatFsAffected
  • =0
Fixed in
  • R0.16

AI-suggested

If you cannot patch yet, avoid using FatFs with FF_LBA64 = 1 on systems where GPT scanning is required, or implement external controls to limit mount-time operations.

Description

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.

References

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