CVE-2026-6686

MEDIUMPre-NVD 4.64.6—
EchelonGraph scoreMEDIUM confidence

Score 4.6 from GitHub Security Advisory published 2026-07-01. a secondary CVSS source baseline 4.6; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this week
4.6EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 4.6Exploit: None knownExposed: 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 an uninitialized cluster exposure when f_lseek() extends files beyond EOF without zero-filling newly allocated clusters. This maps to CWE-908 (Use of Uninitialized Resource). Estimated CVSS v3.1 vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N (4.6, Medium). The estimated CISA SSVC vectors are Exploitation: PoC, Technical Impact: Partial.

CVSS v3
4.6
EG Score
4.6(medium)
EG Risk
25(Track)
EG Risk 25/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity46% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
17%
KEV
Not listed

Published

July 1, 2026

Last Modified

July 2, 2026

Advisory Details (3)

Auto-updated Jul 3, 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 uninitialized cluster exposure after seek beyond EOF

https://www.runzero.com/advisories/fatfs-uninit-cluster-exposure-cve-2026-6686/

Vendor Advisories for CVE-2026-6686(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 14× in last 7d / 81× 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.

Showing the most recent 100 of 146 total refreshes for this CVE.

  1. 2026-08-26 14:47 UTCEPSS rescore
  2. 2026-08-25 13:49 UTCEPSS rescore
  3. 2026-08-25 02:04 UTCEG score recompute
  4. 2026-08-25 02:04 UTCGHSA enrichment
  5. 2026-08-24 04:11 UTCGHSA enrichment
  6. 2026-08-23 05:25 UTCEG score recompute
  7. 2026-08-23 05:25 UTCGHSA enrichment
  8. 2026-08-23 00:19 UTCEPSS rescore
  9. 2026-08-22 07:21 UTCEG score recompute
  10. 2026-08-22 07:21 UTCGHSA enrichment
  11. 2026-08-21 23:49 UTCEPSS rescore
  12. 2026-08-21 04:33 UTCEG score recompute
  13. 2026-08-21 04:33 UTCGHSA enrichment
  14. 2026-08-20 22:56 UTCEPSS rescore
  15. 2026-08-20 04:45 UTCEG score recompute
  16. 2026-08-20 04:45 UTCGHSA enrichment
  17. 2026-08-19 17:04 UTCEPSS rescore
  18. 2026-08-18 21:00 UTCEG score recompute
  19. 2026-08-18 21:00 UTCGHSA enrichment
  20. 2026-08-18 13:49 UTCEPSS rescore
  21. 2026-08-18 13:49 UTCEPSS rescore
  22. 2026-08-17 14:19 UTCEG score recompute
  23. 2026-08-17 14:19 UTCGHSA enrichment
  24. 2026-08-17 13:47 UTCEPSS rescore
  25. 2026-08-16 16:25 UTCEG score recompute
Show 75 more
  1. 2026-08-16 16:25 UTCGHSA enrichment
  2. 2026-08-16 14:56 UTCEPSS rescore
  3. 2026-08-16 14:56 UTCEPSS rescore
  4. 2026-08-16 02:15 UTCEPSS rescore
  5. 2026-08-15 18:33 UTCEG score recompute
  6. 2026-08-15 18:33 UTCGHSA enrichment
  7. 2026-08-15 01:31 UTCEPSS rescore
  8. 2026-08-14 20:40 UTCGHSA enrichment
  9. 2026-08-13 22:48 UTCEG score recompute
  10. 2026-08-13 22:47 UTCGHSA enrichment
  11. 2026-08-13 22:00 UTCEPSS rescore
  12. 2026-08-13 00:54 UTCEG score recompute
  13. 2026-08-13 00:54 UTCGHSA enrichment
  14. 2026-08-12 13:51 UTCEPSS rescore
  15. 2026-08-12 03:02 UTCEG score recompute
  16. 2026-08-12 03:02 UTCGHSA enrichment
  17. 2026-08-11 05:09 UTCEG score recompute
  18. 2026-08-11 05:09 UTCGHSA enrichment
  19. 2026-08-11 00:00 UTCEPSS rescore
  20. 2026-08-10 07:17 UTCEG score recompute
  21. 2026-08-10 07:17 UTCGHSA enrichment
  22. 2026-08-09 13:47 UTCEPSS rescore
  23. 2026-08-09 09:24 UTCEG score recompute
  24. 2026-08-09 09:24 UTCGHSA enrichment
  25. 2026-08-08 16:37 UTCEPSS rescore
  26. 2026-08-08 11:32 UTCEG score recompute
  27. 2026-08-08 11:32 UTCGHSA enrichment
  28. 2026-08-07 13:39 UTCGHSA enrichment
  29. 2026-08-06 15:46 UTCEG score recompute
  30. 2026-08-06 15:46 UTCGHSA enrichment
  31. 2026-08-06 13:47 UTCEPSS rescore
  32. 2026-08-05 19:17 UTCEPSS rescore
  33. 2026-08-05 19:17 UTCEPSS rescore
  34. 2026-08-05 17:54 UTCGHSA enrichment
  35. 2026-08-04 20:02 UTCEG score recompute
  36. 2026-08-04 20:02 UTCGHSA enrichment
  37. 2026-08-04 15:10 UTCEPSS rescore
  38. 2026-08-04 10:39 UTCEPSS rescore
  39. 2026-08-03 22:10 UTCEG score recompute
  40. 2026-08-03 22:10 UTCGHSA enrichment
  41. 2026-08-03 10:36 UTCEPSS rescore
  42. 2026-08-03 00:17 UTCEG score recompute
  43. 2026-08-03 00:17 UTCGHSA enrichment
  44. 2026-08-02 02:27 UTCEPSS rescore
  45. 2026-08-02 02:19 UTCGHSA enrichment
  46. 2026-08-01 04:26 UTCEG score recompute
  47. 2026-08-01 04:26 UTCGHSA enrichment
  48. 2026-08-01 04:16 UTCEPSS rescore
  49. 2026-07-31 06:33 UTCEG score recompute
  50. 2026-07-31 06:33 UTCGHSA enrichment
  51. 2026-07-30 16:28 UTCEPSS rescore
  52. 2026-07-30 08:39 UTCEG score recompute
  53. 2026-07-30 08:39 UTCGHSA enrichment
  54. 2026-07-30 01:30 UTCEPSS rescore
  55. 2026-07-29 08:34 UTCEG score recompute
  56. 2026-07-29 08:34 UTCGHSA enrichment
  57. 2026-07-28 15:37 UTCEPSS rescore
  58. 2026-07-28 09:09 UTCEG score recompute
  59. 2026-07-28 09:09 UTCGHSA enrichment
  60. 2026-07-27 14:14 UTCEPSS rescore
  61. 2026-07-27 11:13 UTCEG score recompute
  62. 2026-07-27 11:13 UTCGHSA enrichment
  63. 2026-07-26 14:54 UTCEPSS rescore
  64. 2026-07-26 13:20 UTCEG score recompute
  65. 2026-07-26 13:20 UTCGHSA enrichment
  66. 2026-07-25 14:18 UTCEPSS rescore
  67. 2026-07-24 14:18 UTCEPSS rescore
  68. 2026-07-24 14:18 UTCEPSS rescore
  69. 2026-07-23 14:18 UTCEPSS rescore
  70. 2026-07-23 14:18 UTCEPSS rescore
  71. 2026-07-23 03:22 UTCEG score recompute
  72. 2026-07-22 14:08 UTCEPSS rescore
  73. 2026-07-22 14:08 UTCEPSS rescore
  74. 2026-07-21 15:25 UTCEPSS rescore
  75. 2026-07-21 15:25 UTCEPSS rescore

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-6686?
CVE-2026-6686 is a medium vulnerability published on July 1, 2026. FatFs R0.16 and earlier contains an uninitialized cluster exposure when f_lseek() extends files beyond EOF without zero-filling newly allocated clusters. This maps to CWE-908 (Use of Uninitialized Resource). Estimated CVSS v3.1 vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N (4.6, Medium). The…
When was CVE-2026-6686 disclosed?
CVE-2026-6686 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-2026-6686 actively exploited?
CVE-2026-6686 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 83.2% of all scored CVEs.
What is the CVSS score of CVE-2026-6686?
CVE-2026-6686 has a CVSS v3 base score of 4.6 (NVD).
How do I remediate CVE-2026-6686?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-6686, 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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