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TI-2026-05862 Aliases CVE-2026-6682GHSA-c25x-vcg6-4ccx

FatFs Integer Overflow in FAT32 Volume Mount

Priority HIGH 68CWE-190Published · Updated

Key facts

Attack vector
Physical
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Code execution
Confidentiality · integrity · availability
High · High · High
Fix status
No fix listed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-190 and the CVSS impact.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00322 25th percentileScored 2026-11-07
Public exploit Yes 3 exploit referencesTagged by NVD
Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
ChaNFatFsup to R0.16—No fix listedCNA
  • FatFs VendorChaN Affected up to R0.16 Fixed in — No fix listed CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:elm-chan:fatfs:*:*:*:*:*:*:*:*up to r0.16VulnerableChaN
  • cpe:2.3:a:elm-chan:fatfs:*:*:*:*:*:*:*:* Versions up to r0.16 Vulnerable ·ChaN

Remediation

No fixed version listed by the sources yet.

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-6682
  2. 2026-10-03 Alias added: GHSA-c25x-vcg6-4ccx

References

Exploit 3

Other 1

  • TI-2026-05867 FatFs Buffer Overflow via Unbounded LFN Filename Copy CVSS 3.1HIGH 7.6
  • TI-2026-05866 FatFs Stack Buffer Overflow via Uncapped exFAT Label Length CVSS 3.1HIGH 7.6
  • TI-2026-05865 FatFs Use of Uninitialized Clusters After Seek Past EOF CVSS 3.1MEDIUM 4.6
  • TI-2026-05864 FatFs Infinite Loop in GPT Partition Scan CVSS 3.1MEDIUM 4.6
  • TI-2026-05863 FatFs Divide-by-Zero in exFAT Sync CVSS 3.1MEDIUM 4.6

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences