CVE-2026-6688

HIGHPre-NVD 7.67.6—
EchelonGraph scoreHIGH confidence

Score 7.6 from GitHub Security Advisory (severity: HIGH) published 2026-07-01. a secondary CVSS source baseline 7.6; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this week
7.6
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 7.6Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

FatFs R0.16 and earlier contains a downstream-caller vulnerability pattern associated with FatFs long filename handling. With LFN enabled, fno.fname can be up to 255 characters; many callers copy it into short fixed buffers without bounds checks, causing overflow. This maps to CWE-120 (Buffer Copy without Checking Size of Input). 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.

CVSS v3
7.6
EG Score
7.6(high)
EPSS
11.3%
KEV
Not listed

Published

July 1, 2026

Last Modified

July 2, 2026

Advisory Details (3)

Auto-updated Jul 2, 2026
⚠️ Active exploitation confirmed. No patch confirmed yet.
generic

GitHub - runZeroInc/vulns-2026-fatfs-chance · GitHub

https://github.com/runZeroInc/vulns-2026-fatfs-chance
generic🔴 Active Exploitation

Seven FatFs bugs, one very large blast radius

https://www.runzero.com/blog/fatfs-bugs/
generic🔴 Active Exploitation

FatFS long filename overflow in downstream callers

https://www.runzero.com/advisories/fatfs-long-fn-of-downstream-cve-2026-6688/

Vendor Advisories for CVE-2026-6688(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 30× in last 7d / 30× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-07 02:43 UTCEG score recompute
  2. 2026-07-07 02:43 UTCGHSA enrichment
  3. 2026-07-06 16:27 UTCEPSS rescore
  4. 2026-07-06 16:27 UTCEPSS rescore
  5. 2026-07-06 13:39 UTCEG score recompute
  6. 2026-07-06 13:39 UTCGHSA enrichment
  7. 2026-07-06 02:23 UTCEPSS rescore
  8. 2026-07-06 02:23 UTCEPSS rescore
  9. 2026-07-06 00:35 UTCEG score recompute
  10. 2026-07-06 00:35 UTCGHSA enrichment
  11. 2026-07-05 11:31 UTCEG score recompute
  12. 2026-07-05 11:31 UTCGHSA enrichment
  13. 2026-07-05 02:31 UTCEPSS rescore
  14. 2026-07-05 02:30 UTCEPSS rescore
  15. 2026-07-04 22:27 UTCEG score recompute
  16. 2026-07-04 22:27 UTCGHSA enrichment
  17. 2026-07-04 09:23 UTCEG score recompute
  18. 2026-07-04 09:23 UTCGHSA enrichment
  19. 2026-07-04 06:31 UTCEPSS rescore
  20. 2026-07-04 06:31 UTCEPSS rescore
  21. 2026-07-03 20:19 UTCEG score recompute
  22. 2026-07-03 20:19 UTCGHSA enrichment
  23. 2026-07-03 07:15 UTCEG score recompute
  24. 2026-07-03 07:15 UTCGHSA enrichment
  25. 2026-07-02 18:11 UTCEG score recompute
Show 5 more
  1. 2026-07-02 18:10 UTCGHSA enrichment
  2. 2026-07-02 05:06 UTCEG score recompute
  3. 2026-07-02 05:06 UTCGHSA enrichment
  4. 2026-07-01 16:02 UTCEG score recompute
  5. 2026-07-01 16:02 UTCGHSA enrichment

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-6688?
CVE-2026-6688 is a high vulnerability published on July 1, 2026. FatFs R0.16 and earlier contains a downstream-caller vulnerability pattern associated with FatFs long filename handling. With LFN enabled, fno.fname can be up to 255 characters; many callers copy it into short fixed buffers without bounds checks, causing overflow. This maps to CWE-120 (Buffer Copy…
When was CVE-2026-6688 disclosed?
CVE-2026-6688 was first published in the National Vulnerability Database on July 1, 2026, with the most recent update on July 2, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-6688 actively exploited?
CVE-2026-6688 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 11.3% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-6688?
CVE-2026-6688 has a CVSS v3 base score of 7.6 (NVD).
How do I remediate CVE-2026-6688?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-6688, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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