Vulnerability report

Trusted Third Party Report Confirmed Confidence In CISA KEV

CVE-2023-21674

Windows 10 Version 1809

Microsoft / Windows 10 Version 1809 · affected before 10.0.17763.3887

Watch CVE-2023-21674 Browse KEV feed
Severity
CVSS 8.8 · High
Confidence
Confirmed
Exploit status
Trusted Third Party Report
EPSS
34.2%
First observed
—
Last observed
—

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

Windows Advanced Local Procedure Call (ALPC) Elevation of Privilege Vulnerability

Have exploitation attempts been observed?

Yes. Exploitation attempts have been reported for this vulnerability. Previdian lists it as a known exploited vulnerability. Listed in CISA KEV. Also reported by third-party sources. Confidence is confirmed.

Who is affected?

Affected products include Microsoft / Windows 10 Version 1809 and 15 other products, including affected before 10.0.17763.3887, affected before 10.0.17763.3887, and affected before 10.0.20348.1487.

What should we do?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Overview

Windows Advanced Local Procedure Call (ALPC) Elevation of Privilege Vulnerability

Windows Advanced Local Procedure Call (ALPC) Elevation of Privilege Vulnerability

Microsoft Affected
Windows 10 Version 1809
Before 10.0.17763.3887
Microsoft Affected
Windows Server 2019
Before 10.0.17763.3887
Microsoft Affected
Windows Server 2019 (Server Core installation)
Before 10.0.17763.3887
Microsoft Affected
Windows Server 2022
Before 10.0.20348.1487
Microsoft Affected
Windows 10 Version 20H2
Before 10.0.19042.2486
Microsoft Affected
Windows 11 version 21H2
Before 10.0.22000.1455
Microsoft Affected
Windows 10 Version 21H2
Before 10.0.19044.2486
Microsoft Affected
Windows 11 version 22H2
Before 10.0.22621.1105
Microsoft Affected
Windows 10 Version 22H2
Before 10.0.19045.2486
Microsoft Affected
Windows 10 Version 1507
Before 10.0.10240.19685
Microsoft Affected
Windows 10 Version 1607
Before 10.0.14393.5648
Microsoft Affected
Windows Server 2016
Before 10.0.14393.5648
Microsoft Affected
Windows Server 2016 (Server Core installation)
Before 10.0.14393.5648
Microsoft Affected
Windows 8.1
Before 6.3.9600.20778
Microsoft Affected
Windows Server 2012 R2
Before 6.3.9600.20778
Microsoft Affected
Windows Server 2012 R2 (Server Core installation)
Before 6.3.9600.20778
View vendor advisory (opens in new tab)
Published
10 Jan 2023
Exploitation Attempts Reported
10 Jan 2023
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None

Tags

nessus_scanner microsoft windows cisa

CVE References

Exploitation evidence

Evidence of exploitation attempts

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploitation Attempts Observed in the Wild

CISA

Recorded 10 Jan 2023

A trusted third party reported exploitation attempts.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

Learn about Pro API access
Source Added
CISA First 2023-01-10 00:00 UTC
Tenable Blog 2026-09-08 18:07 UTC

Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Virtual patch status

No Previdian virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

Scanner Artifacts

Scanner and exploit-framework references linked to this CVE.

Scanner Reference Detected
Nessus https://www.tenable.com/plugins/nessus/169789 02 Jun 2025

Risk and context

Severity, weaknesses, and research context

CVSS v3.1

8.8 High

Potential damage if exploited. Separate from whether attackers are using it.

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

EPSS

34.2%

Estimated chance of exploitation in the next 30 days. Previdian's warning comes from evidence, not this score.

Weaknesses

Use After Free CWE-416

Recent mention · Tenable Blog

Microsoft’s September 2026 Patch Tuesday addresses 964 CVEs (CVE-2026-81963, CVE-2026-85880)

104Critical860Important0Moderate0LowMicrosoft addresses 964 CVEs, smashing July’s release as the largest Patch Tuesday release. This month’s updates include patches for two zero-days that were exploited in the wild.Microsoft patched a record 964 CVEs in its September 2026...

Read full advisory

All Mentions

Recent mention · Tenable Blog

Microsoft’s September 2026 Patch Tuesday addresses 964 CVEs (CVE-2026-81963, CVE-2026-85880)

Tenable Blog · 08 Sep 2026

104Critical860Important0Moderate0LowMicrosoft addresses 964 CVEs, smashing July’s release as the largest Patch Tuesday release. This month’s updates include patches for two zero-days that were exploited in the wild.Microsoft patched a record 964 CVEs in its September 2026 Patch Tuesday release, with 101 rated critical and 824 rated as important.This month’s update includes patches for:.NET.NET and Visual StudioASP.NET CoreActive Directory Certificate Services (AD CS)Active Directory Domain ServicesActive Directory Federation Services (AD FS)Audio Video Control Transport ProtocolAzure...

Timeline

From disclosure to observed exploitation attempts

  1. 18:07 UTC

    KEV confirmed by Tenable Blog

    Exploitation attempts reported by an external source

  2. 09:27 UTC

    Nessus plugin available

    Scanner coverage available

  3. 00:00 UTC

    Added to CISA KEV

    Listed in the CISA Known Exploited Vulnerabilities catalog

  4. 00:00 UTC

    CVE published

    Vulnerability disclosed publicly

  5. 00:00 UTC

    CVE ID reserved

    Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

Start 14-day Pro trial Read API docs
  • Evidence confidence and provenance
  • First-party sensor telemetry
  • PoC and scanner references
  • Affected versions and enrichment
  • Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2023-21674

Sample API response 
{
  "cve_id": "CVE-2023-21674",
  "confidence": "Confirmed",
  "cvss_score": 8.8,
  "cvss_estimated": false,
  "epss_score": 0.34206,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "attempts": 0, "sensors": 0 }
}