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HIGH severity

CVE-2026-62721 — Windows 10 21h2

HIGH

CVE-2026-62721 is a high-severity (CVSS 7.8) CWE-1220 vulnerability in microsoft windows 10 21h2. A fix is available — see the affected versions and patch details below.

Insufficient granularity of access control in User-Mode Power Service (UMPS) allows an authorized attacker to elevate privileges locally.

Published
Aug 11, 2026
Updated
Sep 14, 2026
Affected
13 products
Patched
See advisory
Exploits
None indexed
Exploitation data as of Sep 30, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • A successful exploit gives an attacker total control of the affected component, not partial access.
  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-62721.

EPSS Exploitation Probability

via FIRST.org ↗
0.3%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs20th percentile — riskier than 20% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2026-62721 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 380,526 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Description

Insufficient granularity of access control in User-Mode Power Service (UMPS) allows an authorized attacker to elevate privileges locally.

Affected Products

13 products · 24 configurations
OS
windows 10 21h2microsoft
< 10.0.19044.7663
range
OS
windows 10 22h2microsoft
< 10.0.19045.7663
range
OS
windows 10 1607microsoft
< 10.0.14393.9418
range
OS
windows 10 1809microsoft
< 10.0.17763.9115
range
OS
windows 11 23h2microsoft
< 10.0.22631.7517
range
OS
windows 11 24h2microsoft
< 10.0.26100.9106
range

Detection & mitigation playbook

Vendor / appliance

  1. Detect

    Inventory every microsoft windows 10 21h2 deployment and check each version against the affected-products list above.

  2. Fix

    Apply the microsoft windows 10 21h2 security patch or hotfix for CVE-2026-62721 on the affected version, following the vendor advisory for your exact build.

  3. Workarounds

    Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used. Alongside that, restrict the management interface to trusted networks and apply the vendor's recommended configuration mitigations.

Frequently Asked Questions

Insufficient granularity of access control in User-Mode Power Service (UMPS) allows an authorized attacker to elevate privileges locally.
O3 Security · Runtime Protection

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CVE-2026-62721: Windows 10 21h2 (High 7.8) | O3 Security