CVE-2026-64399

CRITICALPre-NVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-07-25. a secondary CVSS source baseline 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 4 sources updated this week
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 9.8Exploit: None knownExposed: 0

A fix is available — apply it.

In the Linux kernel, the following vulnerability has been resolved:

ksmbd: add permission checks for FSCTL_DUPLICATE_EXTENTS_TO_FILE

The FSCTL_DUPLICATE_EXTENTS_TO_FILE arm of smb2_ioctl() overwrites the destination file's data via vfs_clone_file_range() with neither the share-level KSMBD_TREE_CONN_FLAG_WRITABLE check nor a per-handle fp->daccess check that the other write-bearing arms carry. A client can overwrite destination data on a read-only share, or from a handle opened with only FILE_WRITE_ATTRIBUTES (which still yields an FMODE_WRITE filp). FILE_WRITE_ATTRIBUTES-only destination handle overwrote the file's data via the clone. Add both checks, matching the FSCTL_SET_SPARSE permission fix; require FILE_WRITE_DATA since this writes data.

CVSS v3
9.8
EG Score
9.8(medium)
EG Risk
49(Track)
EG Risk 49/100SSVC: 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
Severity98% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
41%
KEV
Not listed

Published

July 25, 2026

Last Modified

September 4, 2026

Advisory Details (6)

Auto-updated Sep 11, 2026
No patch confirmed yet.
generic

ksmbd: add permission checks for FSCTL_DUPLICATE_EXTENTS_TO_FILE - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/c917e4522d251071dde9871b9142d8ea1186ebfe
generic

ksmbd: add permission checks for FSCTL_DUPLICATE_EXTENTS_TO_FILE - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/bf460ad5958d506492de4524a656439da3f99c51
generic

ksmbd: add permission checks for FSCTL_DUPLICATE_EXTENTS_TO_FILE - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/baae7b39673ec21073a25e3d14f8feaada01d5df
generic

ksmbd: add permission checks for FSCTL_DUPLICATE_EXTENTS_TO_FILE - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/9b9cf7e65cbeaae1b6636144bacee611cdd7a5d6
generic

ksmbd: add permission checks for FSCTL_DUPLICATE_EXTENTS_TO_FILE - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/620d133d469295ee7c017ca6aafac335f65c4a5a
generic

ksmbd: add permission checks for FSCTL_DUPLICATE_EXTENTS_TO_FILE - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/388e4139db27a9e3612c9d356b826f5b1ff6a9e3

Vendor Advisories for CVE-2026-64399(2)

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

Patch Availability(4)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulinux-virtual-hwe-26.04-edge (7.0.0-31.31) @ resolute2026-09-15ubuntu
ubuntulinux-tools-oem-7.0 (7.0.0-1013.13) @ resolute2026-09-15ubuntu
ubuntulinux-tools-gcp-edge (7.0.0-1011.11~24.04.1) @ noble2026-09-15ubuntu
ubuntulinux-tools-nvidia-hwe-24.04-edge (7.0.0-1018.18~24.04.1) @ noble2026-09-15ubuntu

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(5 across 4 ecosystems)
Debian:12(2)
PackageVulnerable rangeFixed inDependents
linux6.1.106-1 ... 6.1.99-1 (55 versions)6.1.180-1—
linux-6.12—6.12.100-1~deb12u1—
Debian:11(1)
PackageVulnerable rangeFixed inDependents
linux-6.16.1.106-3~deb11u1 ... 6.1.177-1~deb11u1 (22 versions)6.1.180-1~deb11u1—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
linux6.12.38-1 ... 6.12.95-1~bpo12+1 (30 versions)6.12.96-1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
linux6.12.100-1 ... 7.1~rc7-1~exp1 (158 versions)7.1.4-1—

All Vendor Advisories

(4)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 54× in last 7d / 176× 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 356 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-64399?
CVE-2026-64399 is a critical vulnerability published on July 25, 2026. In the Linux kernel, the following vulnerability has been resolved: ksmbd: add permission checks for FSCTLDUPLICATEEXTENTSTOFILE The FSCTLDUPLICATEEXTENTSTOFILE arm of smb2_ioctl() overwrites the destination file's data via vfsclonefile_range() with neither the share-level KSMBDTREECONNFLAGWRITABLE…
When was CVE-2026-64399 disclosed?
CVE-2026-64399 was first published in the National Vulnerability Database on July 25, 2026, with the most recent update on September 4, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-64399 actively exploited?
CVE-2026-64399 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 59.2% of all scored CVEs.
What is the CVSS score of CVE-2026-64399?
CVE-2026-64399 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2026-64399?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-64399, 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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