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CVE-2026-83952

INDEX BUILT · 2026-09-20

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Windows Resilient File System (ReFS) Elevation of Privilege Vulnerability

CVE-2026-839524 of 4 sources documented this
25

rank 25 = 0 + 20 + 0 + 5 + 0

rank@v1 · scheduled

Someone is already using it

CISA KEV catalog · public proof-of-concept · FIRST EPSS

EPSS 0.00240  ·  without this subject the record ranks 25

What it costs you if it fires

NVD CVSS base score, then the CNA's own

CVSS 7.8, from the CNA  ·  without this subject the record ranks 5

It is getting worse, not staying still

FIRST EPSS series, rescorings and bad loads removed

no persisting rise in 365 days  ·  without this subject the record ranks 25

How much of the world it touches

NVD CPE configurations

4 products in the CPE ranges  ·  without this subject the record ranks 20

Someone else already set the date

CISA KEV remediation due date

no CISA due date  ·  without this subject the record ranks 25

Unaudited dollar value2 of 3 inputs carry a receipt
Exposure$12,000over the next 30 days, if this record is yours
Movementno material movementthe record holds only daily drift and scoring model releases
Basisassumeda published average, not your estate

$12,000 = $4.99M incident cost x 1 exposure x 0.0024 likelihood

udv@v1 · unaudited · wrong for you until you say what you run

$4.99M is the cost of a breach that happened, from IBM Cost of a Data Breach Report 2026, global average. It is not the value of any asset of yours. That average already covers breaches of every severity, so scaling it by exposure understates a partial-impact record. That is an assumption, not a measurement. Your own asset value goes in the decision record.

Hindsight · the state

0.0024EPSSNOT IN KEVas of 2026-09-20
Severity7.8 HIGHreceipt
Harmtotal lossreceipt
Exploitationnone in held sources
Defensefix version namedreceipt
Movementsteadyreceipt
STEADY10Holding near 0.00 across 2 observations. arc-rules@v1

Foresight · where to check next

Microsoft WindowsMicrosoft WindowsMicrosoft WindowsMicrosoft Windows83952

This record is one instance of CWE-122, heap-based buffer overflow. The index holds 3216 prior instances of this class, 20 KEV-listed. The nearest of its KEV-listed records are drawn beside this. taxonomy@v1

Full pattern panel

Prior records in this weakness class. Each is its own record, dated and receipted.
Color is a claim, not decoration:the hostile worldthe defenseno signalspoke length is how much of the record matches, not how bad it is

Running Microsoft Windows 11 Version 24H2? Check your version

A deterministic range check against the ranges this record publishes. It tells you where a version sits in the record, not whether your deployment is exploitable. No account needed.

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Record your call

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AcceptDeferPatch by…Not affectedMitigated

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Harm, if it fires from the vector and the weakness

Written for the ticket you're about to file.

Reachneeds local access · low privileges required · no user interaction · low attack complexityreceipt
ImpactComplete confidentiality, integrity and availability lossreceipt
Scored fromCVSS v3.1 · the CNA's vectorreceipt
Weakness classCWE-122 Heap-based Buffer Overflowreceipt
Published consequencesCWE-122: Availability: DoS: Crash, Exit, or Restart, DoS: Resource Consumption (CPU), DoS: Resource Consumption (Memory); Integrity, Confidentiality, Availability, Access Control: Execute…[email protected]

CISA KEV & Federal Remediation Deadline from the record and CISA

The fix, and how long it's been waiting.

Fixed in10.0.26100.9445; 10.0.26200.9445; 10.0.28000.2954; 10.0.26100.33438receipt
Patch available sinceNo dated patch-availability record in held sources. The index holds reference URLs without dates and only the current revision of the CVE record, so the day a fix first existed cannot be derived. Only the versions it landed in.

Exploit Status & Known PoCs a ladder, not a score

Current rung: Nothing observed in held sources.

  • RUNG 1Nothing observed in held sources
  • RUNG 2Proof-of-concept published
  • RUNG 3Exploited in the wild · CISA KEV listed
  • RUNG 4Ransomware campaign use known

Authority who says so

CVSS, the CNA7.8 HIGHreceipt
Exploit probability0.0024 · top 85% of all CVEsreceipt
Blast breadth2 products across 1 vendorderived
Assigned bymicrosoftreceipt
Recorded changes2 · last 19 Sep 2026derived

Affected & Fixed Versions as published

Affected productMicrosoft Windows 11 Version 24H2; Microsoft Windows 11 Version 25H2; Microsoft Windows 11 version 26H1; Microsoft Windows Server 2025; Microsoft Windows Server 2025 (Server Core installation)receipt
Published rangesmicrosoft windows 11 24h2 < 10.0.26100.9445; microsoft windows 11 25h2 < 10.0.26200.9445; microsoft windows 11 26h1 < 10.0.28000.2954; microsoft windows server 2025 < 10.0.26100.33438receipt
Fixed in10.0.26100.9445; 10.0.26200.9445; 10.0.28000.2954; 10.0.26100.33438receipt

A rung lights from a row in the index, never from an assessment. "Held sources" is the true scope of the claim: this index reads the CVE record, NVD, CISA KEV, FIRST's EPSS and public proof-of-concept repositories, and it does not observe attacks.

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Attack path

Local accessrequires low privilegesMicrosoft Windows Server 2025CWE-122 weaknessFull compromise (C/I/A)C:H / I:H / A:Hexploits CWE-122data compromise

What it is stated by the CNA

Heap-based buffer overflow in Windows Resilient File System (ReFS) allows an authorized attacker to elevate privileges locally. receipt

NVD's analysis a second authority

weakness
CWE-122
affected versions
microsoft windows 11 24h2 < 10.0.26100.9445; microsoft windows 11 25h2 < 10.0.26200.9445; microsoft windows 11 26h1 < 10.0.28000.2954; and 1 more, listed in full below
also scored by
[email protected] 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

check it yourself msrc.microsoft.com receipt

Movement the material steps

9 Sep 20260.00245
14 Sep 20260.0024
Show all 2 observations
9 Sep 20260.00245
14 Sep 20260.0024

2 observations held. A highlighted step crossed a promotion threshold. A step marked with a scoring model moved because the instrument was replaced, not because the vulnerability changed. receipt

The full biography

EPSS 0.0024Published2026-09-08Index as of2026-09-14

The record had been public for 6 days when this index was last written.

Published 2026-09-08 receipt · Index as of 2026-09-14 derived

The pattern, elsewhere

This record is one instance of CWE-122, heap-based buffer overflow. The index holds 3216 prior instances of this class, 20 KEV-listed. The nearest of its KEV-listed records are drawn beside this. [email protected]

CVE-2024-30051 · Microsoft Windows 10 Version 1809matches 9 of 9KEV listed · 2024receipt
CVE-2023-23376 · Microsoft Windows 10 Version 1507matches 9 of 9KEV listed · 2023receipt
CVE-2023-28252 · Microsoft Windows 10 Version 1809matches 9 of 9KEV listed · 2023receipt
CVE-2026-85880 · Microsoft Windows 10 Version 1607matches 9 of 9KEV listed · 2026receipt
CVE-2025-21333 · Microsoft Windows 10 Version 21H2matches 9 of 9KEV listed · 2025receipt
CVE-2025-21418 · Microsoft Windows 10 Version 1507matches 9 of 9KEV listed · 2025receipt

"Matches n of m" counts the attributes the two records can both be compared on: the CVSS metrics they share a version of, any weakness class beyond this one, and the vendor. fit-rules@v1

3216 records in this class held. The six above are drawn from the ones CISA has listed as exploited, ranked by how much of the record matches this one. That is why every one of them is KEV-listed: the pool is, so the colour on those spokes says nothing the pool has not already said.

No curated product neighbourhood is held for this product, so the records above are the nearest this index can name. The neighbourhood table covers a small set of products and is extended by hand.

Siblings and hubs

Records related to this one

Browse the index from here

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What usually comes next

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