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Response snapshot Oct 26, 2026, 23:55 UTC

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VulnerabilityCVE-2026-21533Known exploitation

Microsoft Windows Improper Privilege Management Vulnerability

Microsoft Windows Remote Desktop Services contains an improper privilege management vulnerability that could allow an authorized attacker to elevate privileges locally.

At a glance

Exploited
Yes: on CISA's Known Exploited list
Severity
7.8 High (CVSS 3.1)
Chance of exploitation
4.1% in the next 30 days
CISA federal deadline
Mar 3, 2026: passed
Sources
2 independent sources

What to do

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Read CISA KEV entry CVE-2026-21533 (opens a new tab)

CISA federal deadline

Federal due date passed

Applies to covered US federal agencies; it is not your organization's deadline.

Added to the catalog Known ransomware use: Unknown
CISA catalog (opens a new tab)

Scores and how they were measured

CVSS base severity

7.8

Version 3.1As of

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

4.1%

Scored Percentile 90.8%

Model and measurement source (opens a new tab)

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

Sources

  1. Primary source

    CISA KEV entry CVE-2026-21533 (opens a new tab)

    The CVE-2026-21533 catalog entry establishes known exploitation, date added, required action, and the federal due date; not zero-day status.

    Published Checked

  2. Primary source

    FIRST measured EPSS score (opens a new tab)

    Measured EPSS probability and percentile for CVE-2026-21533, scored 2026-10-26. This is a model estimate, not proof of exposure.

    Published Checked

  3. Primary source

    CVE Program CNA microsoft (opens a new tab)

    The published CVE-2026-21533 document's CNA supplies this CVSS 3.1 base score, vector, and authoritative source update date.

    Published Checked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, February 10). Microsoft Windows Improper Privilege Management Vulnerability (CVE-2026-21533). https://kevwire.com/record/CVE-2026-21533

MLA

"Microsoft Windows Improper Privilege Management Vulnerability (CVE-2026-21533)." KEVWire, 10 Feb. 2026, kevwire.com/record/CVE-2026-21533.

Chicago

KEVWire. "Microsoft Windows Improper Privilege Management Vulnerability (CVE-2026-21533)." Last modified February 10, 2026. https://kevwire.com/record/CVE-2026-21533.

Evidence summary (plain text)

Microsoft Windows Improper Privilege Management Vulnerability (Feb 10, 2026).
Microsoft Windows Remote Desktop Services contains an improper privilege management vulnerability that could allow an authorized attacker to elevate privileges locally.
CVSS 7.8 (version 3.1; evidence as of Aug 19, 2026; https://cveawg.mitre.org/api/cve/CVE-2026-21533).
EPSS 4.1% for the following 30 days, scored Oct 26, 2026 (https://api.first.org/data/v1/epss?cve=CVE-2026-21533&date=2026-10-26).
Sources:
CISA KEV entry CVE-2026-21533: https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json
FIRST measured EPSS score: https://api.first.org/data/v1/epss?cve=CVE-2026-21533&date=2026-10-26
CVE Program CNA microsoft: https://cveawg.mitre.org/api/cve/CVE-2026-21533
Record ID: CVE-2026-21533.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Documented by a cited source.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
CISA federal due date: Mar 3, 2026. This is a deadline for covered US federal agencies, not the reader's SLA.
About this data

This record was ingested from a data source. Retrieved: Oct 26, 2026, 22:15 UTC. Ingestion is not an independent editorial investigation.

CISA added this entry on 2026-02-10. This record's publication date is the catalog addition date, not necessarily the initial vulnerability disclosure. KEV means known exploitation, not necessarily a zero-day. CISA due dates apply to covered US federal agencies, not your organizational SLA.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

Record JSON

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Record details

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