CVE-2026-64397

CRITICALPre-NVD 9.89.8
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

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, GitHub Security Advisory, a secondary CVSS source
Trending — 4 sources updated this week

Also known asEUVD-2026-48941 (ENISA EUVD) · GHSA-76f2-j4c3-m5v4 (GitHub Security Advisories)Source: ENISA EUVD

9.8EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.5%CVSS: 9.8Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

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

ksmbd: serialize QUERY_DIRECTORY requests per file

smb2_query_dir() stores a pointer to its stack-allocated private data in the ksmbd_file readdir_data. Concurrent QUERY_DIRECTORY requests using the same file handle can overwrite this pointer while an iterate_dir() callback is still using it, resulting in a stack use-after-free.

Add a per-file mutex and hold it while accessing the shared directory enumeration state. The lock covers scan restart, dot entry state, readdir_data setup and iteration, and response construction. This prevents another request from replacing readdir_data.private before the current request has finished using it and also serializes the shared file position.

CVSS v3
9.8
EG Score
9.8CRITICALmedium confidence
EG Risk
44
EG Risk 44/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity98% × 45%
Impact severity (EG Severity): CVSS 9.8 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.5% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's BOD 26-04 default: no one has published Automatable for this CVE, and CISA treats it as “no” for a CVE not in KEV.
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).
Exploitation none (no CISA value, KEV listing or exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from Vulnrichment. EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.5%
EPSS %ILE
41st
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (9.8): severity, escalated by confirmed exploitation. This CVE's 9.8 is its impact severity (EG Severity), not escalated.

EG Severity
9.8 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.5% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-01). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines.

Exploitation none (no CISA value, KEV listing or exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from Vulnrichment. EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). Where an input reads “CISA's BOD 26-04 default”, no one has published it for this CVE, and CISA's implementation guidance says: “If “Automatable” and “Technical Impact” information items about a CVE ID are not available and the CVE ID is not in the KEV Catalog, CISA will treat its values as “no” and “total,” respectively, until CISA or a third party provides metadata about the CVE ID. CISA will always provide the Vulnrichment data for a CVE ID listed in the KEV Catalog.” Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

July 25, 2026

Last Modified

September 4, 2026

Advisory Details (6)

Auto-updated Oct 31, 2026
Patch available.
Web page

ksmbd: serialize QUERY_DIRECTORY requests per file - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/fd22b039a5a05bc1d6818e9dcd1001fb432a829d
Web page

ksmbd: serialize QUERY_DIRECTORY requests per file - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/be6d26bf27499977c746abc163659915082348d8
Web page

ksmbd: serialize QUERY_DIRECTORY requests per file - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/a1d5d31cad593ea5e1b637f2f39c9ef6d09d1199
Web page

ksmbd: serialize QUERY_DIRECTORY requests per file - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/64dac2d486ec1eb18dc00968b16a230b6b75ec24
Web page

ksmbd: serialize QUERY_DIRECTORY requests per file - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/2a64dbf9c739ddf7a25a066507597bf89f8f73d2
Web page

ksmbd: serialize QUERY_DIRECTORY requests per file - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/1426fd79102539bc0ab5c8fced047ad4313b9908

Vendor Advisories for CVE-2026-64397(2)

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

Patch Availability(14)

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 rangeFix by version rangeDependents
linux6.1.106-1 ... 6.1.99-1 (55 versions)
  • every version up to 6.1.180-1: fixed in 6.1.180-1
—
linux-6.12—
  • every version up to 6.12.100-1~deb12u1: fixed in 6.12.100-1~deb12u1
—
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
linux-6.16.1.106-3~deb11u1 ... 6.1.177-1~deb11u1 (22 versions)
  • every version up to 6.1.180-1~deb11u1: fixed in 6.1.180-1~deb11u1
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
linux6.12.38-1 ... 6.12.95-1~bpo12+1 (30 versions)
  • every version up to 6.12.96-1: fixed in 6.12.96-1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
linux6.12.100-1 ... 7.1~rc7-1~exp1 (159 versions)
  • every version up to 7.1.4-1: fixed in 7.1.4-1
—

Weakness Classification(1)

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

All Vendor Advisories

(14)

Data Freshness Timeline

(refreshed 27× in last 7d / 98× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 100 of 564 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 464 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-02 16:45 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  2. 2026-11-02 09:52 UTCEG score recompute
  3. 2026-11-02 09:52 UTCVendor advisory
  4. 2026-11-02 09:52 UTCGHSA enrichmentGHSA-76f2-j4c3-m5v4 · GitHub severity CRITICAL · GitHub CVSS 9.8
  5. 2026-11-01 16:35 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  6. 2026-11-01 09:12 UTCEG score recompute
  7. 2026-11-01 09:12 UTCVendor advisory
  8. 2026-11-01 09:11 UTCGHSA enrichmentGHSA-76f2-j4c3-m5v4 · GitHub severity CRITICAL · GitHub CVSS 9.8
  9. 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  10. 2026-10-31 08:32 UTCEG score recompute
  11. 2026-10-31 08:32 UTCVendor advisory
  12. 2026-10-31 08:32 UTCGHSA enrichmentGHSA-76f2-j4c3-m5v4 · GitHub severity CRITICAL · GitHub CVSS 9.8
  13. 2026-10-30 16:35 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  14. 2026-10-30 07:51 UTCEG score recompute
  15. 2026-10-30 07:51 UTCVendor advisory
  16. 2026-10-30 07:51 UTCGHSA enrichmentGHSA-76f2-j4c3-m5v4 · GitHub severity CRITICAL · GitHub CVSS 9.8
  17. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  18. 2026-10-29 07:11 UTCEG score recompute
  19. 2026-10-29 07:11 UTCVendor advisory
  20. 2026-10-29 07:11 UTCGHSA enrichmentGHSA-76f2-j4c3-m5v4 · GitHub severity CRITICAL · GitHub CVSS 9.8
  21. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  22. 2026-10-28 06:31 UTCEG score recompute
  23. 2026-10-28 06:31 UTCVendor advisory
  24. 2026-10-28 06:31 UTCGHSA enrichmentGHSA-76f2-j4c3-m5v4 · GitHub severity CRITICAL · GitHub CVSS 9.8
  25. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.5% · 41st percentile
Show 75 more
  1. 2026-10-27 05:51 UTCEG score recompute
  2. 2026-10-27 05:51 UTCGHSA enrichmentGHSA-76f2-j4c3-m5v4 · GitHub severity CRITICAL · GitHub CVSS 9.8
  3. 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  4. 2026-10-26 01:07 UTCEG score recompute
  5. 2026-10-26 01:07 UTCVendor advisory
  6. 2026-10-26 01:07 UTCGHSA enrichmentGHSA-76f2-j4c3-m5v4 · GitHub severity CRITICAL · GitHub CVSS 9.8
  7. 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  8. 2026-10-25 14:12 UTCEG score recompute
  9. 2026-10-25 00:26 UTCEG score recompute
  10. 2026-10-25 00:26 UTCVendor advisory
  11. 2026-10-25 00:25 UTCGHSA enrichmentGHSA-76f2-j4c3-m5v4 · GitHub severity CRITICAL · GitHub CVSS 9.8
  12. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  13. 2026-10-23 23:45 UTCEG score recompute
  14. 2026-10-23 23:45 UTCVendor advisory
  15. 2026-10-23 23:45 UTCGHSA enrichmentGHSA-76f2-j4c3-m5v4 · GitHub severity CRITICAL · GitHub CVSS 9.8
  16. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  17. 2026-10-22 23:04 UTCEG score recompute
  18. 2026-10-22 23:04 UTCVendor advisory
  19. 2026-10-22 23:04 UTCGHSA enrichmentGHSA-76f2-j4c3-m5v4 · GitHub severity CRITICAL · GitHub CVSS 9.8
  20. 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  21. 2026-10-21 22:25 UTCEG score recompute
  22. 2026-10-21 22:24 UTCGHSA enrichmentGHSA-76f2-j4c3-m5v4 · GitHub severity CRITICAL · GitHub CVSS 9.8
  23. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  24. 2026-10-20 21:42 UTCEG score recompute
  25. 2026-10-20 21:42 UTCVendor advisory
  26. 2026-10-20 21:42 UTCGHSA enrichmentGHSA-76f2-j4c3-m5v4 · GitHub severity CRITICAL · GitHub CVSS 9.8
  27. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  28. 2026-10-19 21:02 UTCEG score recompute
  29. 2026-10-19 21:01 UTCGHSA enrichmentGHSA-76f2-j4c3-m5v4 · GitHub severity CRITICAL · GitHub CVSS 9.8
  30. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  31. 2026-10-18 19:46 UTCEG score recompute
  32. 2026-10-18 19:46 UTCGHSA enrichmentGHSA-76f2-j4c3-m5v4 · GitHub severity CRITICAL · GitHub CVSS 9.8
  33. 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  34. 2026-10-18 03:22 UTCEG score recompute
  35. 2026-10-17 19:04 UTCEG score recompute
  36. 2026-10-17 19:04 UTCVendor advisory
  37. 2026-10-17 19:04 UTCGHSA enrichmentGHSA-76f2-j4c3-m5v4 · GitHub severity CRITICAL · GitHub CVSS 9.8
  38. 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  39. 2026-10-16 18:24 UTCEG score recompute
  40. 2026-10-16 18:24 UTCGHSA enrichmentGHSA-76f2-j4c3-m5v4 · GitHub severity CRITICAL · GitHub CVSS 9.8
  41. 2026-10-16 16:43 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  42. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  43. 2026-10-15 14:56 UTCEG score recompute
  44. 2026-10-15 14:55 UTCGHSA enrichmentGHSA-76f2-j4c3-m5v4 · GitHub severity CRITICAL · GitHub CVSS 9.8
  45. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  46. 2026-10-14 09:23 UTCEG score recompute
  47. 2026-10-14 09:23 UTCGHSA enrichmentGHSA-76f2-j4c3-m5v4 · GitHub severity CRITICAL · GitHub CVSS 9.8
  48. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  49. 2026-10-13 06:50 UTCEG score recompute
  50. 2026-10-13 06:49 UTCGHSA enrichmentGHSA-76f2-j4c3-m5v4 · GitHub severity CRITICAL · GitHub CVSS 9.8
  51. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  52. 2026-10-12 15:48 UTCEG score recompute
  53. 2026-10-12 06:09 UTCVendor advisory
  54. 2026-10-12 06:09 UTCGHSA enrichmentGHSA-76f2-j4c3-m5v4 · GitHub severity CRITICAL · GitHub CVSS 9.8
  55. 2026-10-11 19:32 UTCEG score recompute
  56. 2026-10-11 16:47 UTCEG score recompute
  57. 2026-10-11 14:09 UTCEG score recompute
  58. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  59. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  60. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  61. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  62. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  63. 2026-10-07 04:34 UTCEG score recompute
  64. 2026-10-07 04:34 UTCVendor advisory
  65. 2026-10-07 04:34 UTCGHSA enrichmentGHSA-76f2-j4c3-m5v4 · GitHub severity CRITICAL · GitHub CVSS 9.8
  66. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  67. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  68. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  69. 2026-10-04 12:40 UTCVendor advisory
  70. 2026-10-04 12:40 UTCGHSA enrichmentGHSA-76f2-j4c3-m5v4 · GitHub severity CRITICAL · GitHub CVSS 9.8
  71. 2026-10-04 07:31 UTCEG score recompute
  72. 2026-10-04 07:31 UTCVendor advisory
  73. 2026-10-04 07:31 UTCGHSA enrichmentGHSA-76f2-j4c3-m5v4 · GitHub severity CRITICAL · GitHub CVSS 9.8
  74. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  75. 2026-10-03 03:15 UTCVendor advisory

Frequently asked(5)

What is CVE-2026-64397?
CVE-2026-64397 is a critical-severity vulnerability; its CVE record was published on July 25, 2026. In the Linux kernel, the following vulnerability has been resolved: ksmbd: serialize QUERY_DIRECTORY requests per file smb2_query_dir() stores a pointer to its stack-allocated private data in the ksmbd_file readdir_data. Concurrent QUERY_DIRECTORY requests using the same file handle can overwrite…
When was the CVE record for CVE-2026-64397 published?
The CVE record for CVE-2026-64397 was published on July 25, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of September 4, 2026; the record at its source may have been updated since.
Is CVE-2026-64397 actively exploited?
CVE-2026-64397 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (41st percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-64397?
CVE-2026-64397 has a CVSS base score of 9.8 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-64397?
A fix for CVE-2026-64397 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-64397 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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