vciy

CVE-2026-20817

INDEX BUILT · 2026-09-20

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Windows Error Reporting Service Elevation of Privilege Vulnerability

CVE-2026-208174 of 4 sources documented this
43

rank 43 = 16 + 20 + 0 + 7 + 0

rank@v1 · scheduled

Someone is already using it

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

EPSS 0.05502  ·  without this subject the record ranks 27

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 23

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 43

How much of the world it touches

NVD CPE configurations

8 products in the CPE ranges  ·  without this subject the record ranks 36

Someone else already set the date

CISA KEV remediation due date

no CISA due date  ·  without this subject the record ranks 43

Unaudited dollar value2 of 3 inputs carry a receipt
Exposure$275,000over 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

$275,000 = $4.99M incident cost x 1 exposure x 0.05502 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

0.05502EPSSNOT IN KEVas of 2026-09-20
Severity7.8 HIGHreceipt
Harmtotal lossreceipt
Exploitationpublic proof-of-conceptreceipt
Defensefix version namedreceipt
Movementdoubled within 72hreceipt
PLATEAU10Minimal movement since 2026-01-14, 239 days at 0.06, as of 2026-09-10. arc-rules@v1

Foresight · where to check next

No weakness class or product neighbourhood is held for this record, so this index cannot name anywhere to check next. That is an absence in the record, not a finding about the software.

Color is a claim, not decoration:the hostile worldthe defenseno signal

Running Microsoft Windows 10 Version 21H2? Check your version

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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-280 Improper Handling of Insufficient Permissions or Privilegesreceipt
Published consequencesCWE-280: Other: Other, Alter Execution Logic[email protected]

CISA KEV & Federal Remediation Deadline from the record and CISA

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

Fixed in10.0.19044.6809; 10.0.19045.6809; 10.0.22631.6491; 10.0.26100.7623; 10.0.26200.7623; 10.0.20348.4648; 10.0.25398.2092; 10.0.26100.32230receipt
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: Proof-of-concept published · 1 public repository, 2026-02-18.

  • RUNG 1Nothing observed in held sources
  • RUNG 2Proof-of-concept published · 1 public repository2026-02-18receipt
  • RUNG 3Exploited in the wild · CISA KEV listed
  • RUNG 4Ransomware campaign use known

Authority who says so

CVSS, the CNA7.8 HIGHreceipt
Exploit probability0.05502 · top 8% of all CVEsreceipt
Blast breadth2 products across 1 vendorderived
Assigned bymicrosoftreceipt
Recorded changes19 · last 19 Sep 2026derived

Affected & Fixed Versions as published

Affected productMicrosoft Windows 10 Version 21H2; Microsoft Windows 10 Version 22H2; Microsoft Windows 11 version 23H2; Microsoft Windows 11 Version 23H2; Microsoft Windows 11 Version 24H2…receipt
Published rangesmicrosoft windows 10 21h2 < 10.0.19044.6809; microsoft windows 10 22h2 < 10.0.19045.6809; microsoft windows 11 23h2 < 10.0.22631.6491; microsoft windows 11 24h2 < 10.0.26100.7623receipt
Show all 8 published ranges
microsoft windows 10 21h2 < 10.0.19044.6809
microsoft windows 10 22h2 < 10.0.19045.6809
microsoft windows 11 23h2 < 10.0.22631.6491
microsoft windows 11 24h2 < 10.0.26100.7623
microsoft windows 11 25h2 < 10.0.26200.7623
microsoft windows server 2022 < 10.0.20348.4648
microsoft windows server 2022 23h2 < 10.0.25398.2092
microsoft windows server 2025 < 10.0.26100.32230
Fixed in10.0.19044.6809; 10.0.19045.6809; 10.0.22631.6491; 10.0.26100.7623; 10.0.26200.7623; 10.0.20348.4648; 10.0.25398.2092; 10.0.26100.32230receipt

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 2022CWE-280 weaknessFull compromise (C/I/A)C:H / I:H / A:Hexploits CWE-280data compromise

What it is stated by the CNA

Improper handling of insufficient permissions or privileges in Windows Error Reporting allows an authorized attacker to elevate privileges locally. receipt

NVD's analysis a second authority

weakness
CWE-280
affected versions
microsoft windows 10 21h2 < 10.0.19044.6809; microsoft windows 10 22h2 < 10.0.19045.6809; microsoft windows 11 23h2 < 10.0.22631.6491; and 5 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

14 Jan 20260.00056
15 Jun 20260.04744 · scoring model v2026.06.15
10 Sep 20260.05502

This score more than doubled inside 72 hours. Both observations are in the full history below.

Show all 14 observations
14 Jan 20260.00056
19 Jan 20260.00061
14 Feb 20260.0007
18 Feb 20260.00019
22 Mar 20260.00023
13 Apr 20260.00031
15 May 20260.00044
27 May 20260.00103
11 Jun 20260.00087
12 Jun 20260.00076
15 Jun 20260.04744
23 Jun 20260.05333
12 Aug 20260.05426
10 Sep 20260.05502

14 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 0.05502Published2026-01-13Public PoC2026-02-18Index as of2026-09-10

Exploit probability more than doubled between 2026-06-12 and 2026-06-15 (0.00076 → 0.04744) and the record had been public for 7 months when this index was last written.

Published 2026-01-13 receipt · Public PoC 2026-02-18 receipt · Index as of 2026-09-10 derived

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