CVE-2023-21674Known exploitationPublic exploit

SYSTEM privilege escalation via ALPC use-after-free

Published Jan 10, 2023 · Updated Oct 21, 2025

A use-after-free in Windows ALPC allows local users with low privileges to escape a browser sandbox and gain SYSTEM privileges. The kernel mishandles the lifetime of a synchronous ALPC request, permitting attacker-controlled reuse of freed message memory. Exploitation requires local code execution; successful reuse crosses the sandbox boundary and executes with SYSTEM authority.

CVSS severity8.8
High
EPSS probability41.81%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A use-after-free in Windows ALPC allows local users with low privileges to escape a browser sandbox and gain SYSTEM privileges. The kernel mishandles the lifetime of a synchronous ALPC request, permitting attacker-controlled reuse of freed message memory. Exploitation requires local code execution; successful reuse crosses the sandbox boundary and executes with SYSTEM authority.

The record

CVE
CVE-2023-21674
Published
Jan 10, 2023
Updated
Oct 21, 2025
Vendor
Microsoft
Product
Windows 10 Version 1507
Classifications
CWE-416, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 10, 2023CVE publishedPublication date reported by the CVE source.
  2. Oct 21, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=10.0.10240.0 <10.0.10240.19685

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Microsoft · Windows 10 Version 1507version=10.0.10240.0 <10.0.10240.19685
Microsoft · Windows Server 2019version=10.0.17763.0 <10.0.17763.3887
Microsoft · Windows 8.1version=6.3.0 <6.3.9600.20778
Microsoft · Windows Server 2016 (Server Core installation)version=10.0.14393.0 <10.0.14393.5648
Microsoft · Windows 11 version 21H2version=10.0.0 <10.0.22000.1455
Microsoft · Windows 10 Version 21H2version=10.0.19043.0 <10.0.19044.2486
Microsoft · Windows Server 2016version=10.0.14393.0 <10.0.14393.5648
Microsoft · Windows 10 Version 20H2version=10.0.0 <10.0.19042.2486
Microsoft · Windows 10 Version 22H2version=10.0.19045.0 <10.0.19045.2486
Microsoft · Windows Server 2012 R2 (Server Core installation)version=6.3.9600.0 <6.3.9600.20778
Microsoft · Windows Server 2019 (Server Core installation)version=10.0.17763.0 <10.0.17763.3887
Microsoft · Windows 11, version 22H2version=10.0.22621.0 <10.0.22621.1105
Microsoft · Windows 10 Version 1607version=10.0.14393.0 <10.0.14393.5648
Microsoft · Windows Server 2022version=10.0.20348.0 <10.0.20348.1487
Microsoft · Windows 10 Version 1809version=10.0.0 <10.0.17763.3887; version=10.0.17763.0 <10.0.17763.3887
Microsoft · Windows Server 2012 R2version=6.3.9600.0 <6.3.9600.20778

Published CVSS scores

8.8Microsoft CorporationCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationReported
Public exploitPublished

Weakness, pattern, technique

CWE-416Use After Free
T1068Exploitation for Privilege Escalation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Reported exploitation

Technologies

Your stack

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Your stack

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