CVE-2026-40406

HIGHPre-NVD 7.57.5
EchelonGraph scoreMEDIUM confidence

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

Score 7.5 from GitHub Security Advisory (severity: HIGH) published 2026-05-12. The CNA's CVSS baseline 7.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: the CNA's CVSS, EPSS, GitHub Security Advisory
Trending — 3 sources updated this week
7.5EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1.0%CVSS: 7.5Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

Use after free in Windows TCP/IP allows an unauthorized attacker to disclose information over a network.

CVSS v3
7.5
EG Score
7.5HIGHmedium confidence
EG Risk
49
EG Risk 49/100

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)
Severity75% × 45%
Impact severity (EG Severity): CVSS 7.5 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation1.0% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (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 at low or medium mission impact and sooner than that at high.
EPSS PROB
1.0%
EPSS %ILE
63rd
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 (7.5): severity, escalated by confirmed exploitation. This CVE's 7.5 is its impact severity (EG Severity), not escalated.

EG Severity
7.5 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
1.0% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-17). 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; Attend at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source: the SSVC and BOD 26-04 blocks below.

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

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (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; 60 days if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). 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

May 12, 2026

Last Modified

August 10, 2026

Advisory Details (1)

Auto-updated May 15, 2026
Patch available. Sources: microsoft.
MicrosoftMentions a patch (unverified)

Security Update Guide - Microsoft Security Response Center

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40406

Vendor Advisories for CVE-2026-40406(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 10× in last 7d / 31× 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 99 of 297 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. 1 repeat row among the latest 100 is merged into the row it repeats. The 198 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-20 16:33 UTCEPSS rescoreEPSS 1.0% · 63rd percentile
  2. 2026-10-19 16:32 UTCEPSS rescoreEPSS 1.0% · 63rd percentile
  3. 2026-10-18 16:32 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
  4. 2026-10-18 03:42 UTCEG score recompute
  5. 2026-10-17 16:34 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
  6. 2026-10-17 14:52 UTCEG score recompute
  7. 2026-10-17 14:51 UTCGHSA enrichmentGHSA-37x6-37vf-qf3r · GitHub severity HIGH · GitHub CVSS 7.5
  8. 2026-10-16 16:42 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
  9. 2026-10-15 16:32 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
  10. 2026-10-14 16:33 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
  11. 2026-10-13 16:34 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
  12. 2026-10-12 16:34 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
  13. 2026-10-12 16:09 UTCEG score recompute
  14. 2026-10-11 19:51 UTCEG score recompute
  15. 2026-10-11 17:05 UTCEG score recompute
  16. 2026-10-11 14:31 UTCEG score recompute
  17. 2026-10-11 13:48 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
  18. 2026-10-10 20:00 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
  19. 2026-10-09 20:07 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
  20. 2026-10-08 17:12 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
  21. 2026-10-07 23:48 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
  22. 2026-10-06 15:17 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
  23. 2026-10-05 17:43 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
  24. 2026-10-04 23:22 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
  25. 2026-10-03 14:25 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
Show 74 more
  1. 2026-10-01 19:50 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
  2. 2026-09-30 15:03 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
  3. 2026-09-27 13:48 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
  4. 2026-09-26 15:58 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
  5. 2026-09-23 17:53 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  6. 2026-09-20 20:15 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  7. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  8. 2026-09-17 19:30 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  9. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  10. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  11. 2026-09-15 03:11 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  12. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  13. 2026-09-12 15:01 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  14. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  15. 2026-09-11 09:37 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  16. 2026-09-10 09:34 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  17. 2026-09-08 22:00 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  18. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  19. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  20. 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  21. 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  22. 2026-09-01 13:53 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  23. 2026-09-01 04:39 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  24. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  25. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  26. 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  27. 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  28. 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  29. 2026-08-25 13:49 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  30. 2026-08-23 18:14 UTCEG score recompute
  31. 2026-08-23 18:14 UTCVendor advisory
  32. 2026-08-23 18:14 UTCGHSA enrichmentGHSA-37x6-37vf-qf3r · GitHub severity HIGH · GitHub CVSS 7.5
  33. 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  34. 2026-08-21 23:49 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  35. 2026-08-20 22:55 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  36. 2026-08-19 17:03 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  37. 2026-08-18 13:48 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  38. 2026-08-17 10:51 UTCEG score recompute
  39. 2026-08-17 10:51 UTCVendor advisory
  40. 2026-08-17 10:51 UTCGHSA enrichmentGHSA-37x6-37vf-qf3r · GitHub severity HIGH · GitHub CVSS 7.5
  41. 2026-08-16 14:56 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  42. 2026-08-16 04:13 UTCEG score recompute
  43. 2026-08-16 04:13 UTCVendor advisory
  44. 2026-08-16 04:13 UTCGHSA enrichmentGHSA-37x6-37vf-qf3r · GitHub severity HIGH · GitHub CVSS 7.5
  45. 2026-08-16 02:14 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  46. 2026-08-15 01:30 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  47. 2026-08-14 14:51 UTCVendor advisory
  48. 2026-08-14 14:51 UTCGHSA enrichmentGHSA-37x6-37vf-qf3r · GitHub severity HIGH · GitHub CVSS 7.5
  49. 2026-08-14 02:43 UTCEG score recompute
  50. 2026-08-14 02:43 UTCVendor advisory
  51. 2026-08-14 02:43 UTCGHSA enrichmentGHSA-37x6-37vf-qf3r · GitHub severity HIGH · GitHub CVSS 7.5
  52. 2026-08-13 22:00 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  53. 2026-08-13 04:08 UTCGHSA enrichmentGHSA-37x6-37vf-qf3r · GitHub severity HIGH · GitHub CVSS 7.5
  54. 2026-08-12 16:01 UTCEG score recompute
  55. 2026-08-12 16:01 UTCVendor advisory
  56. 2026-08-12 16:01 UTCGHSA enrichmentGHSA-37x6-37vf-qf3r · GitHub severity HIGH · GitHub CVSS 7.5
  57. 2026-08-12 13:51 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  58. 2026-08-11 15:43 UTCEG score recompute
  59. 2026-08-11 15:43 UTCVendor advisory
  60. 2026-08-11 15:43 UTCGHSA enrichmentGHSA-37x6-37vf-qf3r · GitHub severity HIGH · GitHub CVSS 7.5
  61. 2026-08-11 13:43 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  62. 2026-08-11 03:36 UTCEG score recompute
  63. 2026-08-11 03:36 UTCVendor advisory
  64. 2026-08-11 03:35 UTCGHSA enrichmentGHSA-37x6-37vf-qf3r · GitHub severity HIGH · GitHub CVSS 7.5
  65. 2026-08-11 00:00 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  66. 2026-08-10 15:28 UTCGHSA enrichmentGHSA-37x6-37vf-qf3r · GitHub severity HIGH · GitHub CVSS 7.5
  67. 2026-08-10 02:19 UTCGHSA enrichmentGHSA-37x6-37vf-qf3r · GitHub severity HIGH · GitHub CVSS 7.5
  68. 2026-08-09 14:12 UTCEG score recompute
  69. 2026-08-09 14:12 UTCVendor advisory
  70. 2026-08-09 14:12 UTCGHSA enrichmentGHSA-37x6-37vf-qf3r · GitHub severity HIGH · GitHub CVSS 7.5
  71. 2026-08-09 13:46 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  72. 2026-08-09 02:04 UTCEG score recompute
  73. 2026-08-09 02:04 UTCVendor advisory
  74. 2026-08-09 02:04 UTCGHSA enrichmentGHSA-37x6-37vf-qf3r · GitHub severity HIGH · GitHub CVSS 7.5

Frequently asked(5)

What is CVE-2026-40406?
CVE-2026-40406 is a high-severity vulnerability; its CVE record was published on May 12, 2026. Use after free in Windows TCP/IP allows an unauthorized attacker to disclose information over a network.
When was CVE-2026-40406 made public?
CVE-2026-40406 was made public on May 12, 2026: that is the date its CVE record's CNA, Microsoft Corporation, gives for when the vulnerability was made public. The CVE record itself was published on May 12, 2026. EchelonGraph's copy of the record carries a last-modified date of August 10, 2026; the record at its source may have been updated since.
Is CVE-2026-40406 actively exploited?
CVE-2026-40406 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1.0% probability of exploitation in the next 30 days (63rd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-40406?
CVE-2026-40406 has a CVSS base score of 7.5 (the CNA's own assessment, by microsoft; NVD's own analysis pending).
How do I remediate CVE-2026-40406?
A fix for CVE-2026-40406 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-40406 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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