CVE-2023-21674: Microsoft Windows Advanced Local Procedure Call (ALPC) Privilege Escalation Vulnerability

Is it exploited?

Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 10 Jan 2023, the same day the CVE record was published.

How likely is exploitation in the next 30 days?

34.2%

EPSS score, percentile 98.4 of all scored records

How severe?

8.8 High

CVSS v3.1 base score, given by the CNA

What should I do?

CISA deadline 31 Jan 2023. Apply updates per vendor instructions.

Advisories and patches (1)

Which versions are affected?

Affected

• from 10.0.17763.0 to before 10.0.17763.3887
• from 10.0.0 to before 10.0.17763.3887
• from 10.0.17763.0 to before 10.0.17763.3887
• from 10.0.17763.0 to before 10.0.17763.3887
• from 10.0.20348.0 to before 10.0.20348.1487
• from 10.0.0 to before 10.0.19042.2486

and 11 more in the table below

Versions by product

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

What to do

CISA due date for this action: 31 January 2023.

Advisories and patches

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

Linked from CISA's catalog entry

• https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2023-21674
• https://nvd.nist.gov/vuln/detail/CVE-2023-21674

Affected products and versions

As listed in the CVE record.

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

About this vulnerability

Microsoft Windows Advanced Local Procedure Call (ALPC) contains an unspecified vulnerability that allows for privilege escalation.

Summary: CISA's KEV catalog, as of 28 Oct 2026.

• CISA added CVE-2023-21674 to its Known Exploited Vulnerabilities (KEV) catalog on 10 Jan 2023.
• CISA's ransomware flag for this entry is "Unknown": no evidence of ransomware use in the catalog, which is not proof of none.
• The due date CISA sets for the required action is 31 Jan 2023.
• The CVE record was published on 10 Jan 2023, the same day it was added to KEV.
• The CVE record carries a CVSS v3.1 base score of 8.8 (High), given by its CNA.
• FIRST's EPSS model puts the probability of exploitation in the next 30 days at 34.2% (percentile 98.4), as of 28 Oct 2026.
• CISA's SSVC assessment in the CVE record: exploitation active, automatable no, technical impact total.

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026. About the data.

Description

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

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

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

Weakness

• CWE-416: Use After Free

CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.

Timeline

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