CVE-2026-6684
FatFs Infinite Loop in GPT Partition Scan
- State
- Published
- Severity
- 4.6 Medium
- Published
- Jul 1, 2026
- Updated
- Jul 1, 2026
- Reserved
- Apr 20, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 4.6 Medium | CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | runZero |
Weaknesses
- CWE-835 Loop with unreachable exit condition ('infinite loop')
Affected Products
| Product | Versions |
|---|---|
FatFsChaN |
|
References
- https://www.runzero.com/blog/fatfs-bugs/third-party-advisory
- https://github.com/runZeroInc/vulns-2026-fatfs-chancetechnical-description
- https://elm-chan.org/fsw/ff/product
- https://www.runzero.com/advisories/fatfs-gpt-scan-loop-dos-cve-2026-6684/third-party-advisory
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