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Fencer Vulns
high 7.8

CVE-2026-20817 json

Windows Error Reporting Service Elevation of Privilege Vulnerability

published 2026-01-13 9 mo ago modified 2026-07-30 3 mo ago also EUVD-2026-2188

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
5.4%
EPSS 5.4% chance of exploitation in 30 days, percentile 92%
public exploits
0
none known

Summary

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

Patch / fix

  • Microsoft Windows 10 Version 21H2 10.0.19044.6809
  • Microsoft Windows 10 Version 22H2 10.0.19045.6809
  • Microsoft Windows 11 version 23H2 10.0.22631.6491
  • Microsoft Windows 11 Version 24H2 10.0.26100.7623
  • Microsoft Windows 11 Version 25H2 10.0.26200.7623
  • Microsoft Windows Server 2022 10.0.20348.4648
  • Microsoft Windows Server 2022, 23H2 Edition (Server Core installation) 10.0.25398.2092
  • Microsoft Windows Server 2025 10.0.26100.32230
  • Microsoft Windows Server 2025 (Server Core installation) 10.0.26100.32230

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
9 mo ago

Exploit prediction

5.42% chance of exploitation in the next 30 days, higher than 92% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Microsoft Windows 10 Version 21H2
  • Microsoft Windows 10 Version 22H2
  • Microsoft Windows 11 version 23H2
  • Microsoft Windows 11 Version 24H2
  • Microsoft Windows 11 Version 25H2
  • Microsoft Windows Server 2022
  • Microsoft Windows Server 2022, 23H2 Edition (Server Core installation)
  • Microsoft Windows Server 2025
  • Microsoft Windows Server 2025 (Server Core installation)

Classification

Weakness
  • CWE-280 Improper Handling of Insufficient Permissions or Privileges

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.