CVE-2023-21674
Windows Advanced Local Procedure Call (ALPC) Elevation of Privilege Vulnerability
- CVSS
- 8.8Highscored by the publisher (CNA)
- Exploited in the wild
- Yes, in CISA KEV since 10 Jan 2023CISA deadline for US federal agencies: 31 Jan 2023unvetted proof-of-concept code on github
- EPSS
- 34.2%chance of exploitation in the next 30 daystop 2% of scored CVEsFIRST score of 11 Nov 2026
- Fix
- Patch availablesee the advisories in the references
- Published
- 10 Jan 2023analysed here 12 Nov 2026
Do first. Apply updates per vendor instructions. (CISA's required action for this KEV entry)
Summary
Triage
The summary, impact and action text on this page are written by our AI analysis pipeline, or taken from the NVD description when a CVE was imported from NVD. They are not the vendor's wording: check them against the sources. A longer AI executive summary and technical analysis are generated for signed-in accounts on the Max plan.
Affected products
| Product | Affected versions | Vendor says fixed in |
|---|---|---|
| Microsoft Windows 10 Version 1507 | >= 10.0.10240.0 and < 10.0.10240.19685Vendor says fixed in: not stated | |
| Microsoft Windows 10 Version 1607 | >= 10.0.14393.0 and < 10.0.14393.5648Vendor says fixed in: not stated | |
| Microsoft Windows 10 Version 1809 | >= 10.0.17763.0 and < 10.0.17763.3887>= 10.0.0 and < 10.0.17763.3887Vendor says fixed in: not stated | |
| Microsoft Windows 10 Version 20H2 | >= 10.0.0 and < 10.0.19042.2486Vendor says fixed in: not stated | |
| Microsoft Windows 10 Version 21H2 | >= 10.0.19043.0 and < 10.0.19044.2486Vendor says fixed in: not stated | |
| Microsoft Windows 10 Version 22H2 | >= 10.0.19045.0 and < 10.0.19045.2486Vendor says fixed in: not stated | |
| Microsoft Windows 11 version 21H2 | >= 10.0.0 and < 10.0.22000.1455Vendor says fixed in: not stated | |
| Microsoft Windows 11 version 22H2 | >= 10.0.22621.0 and < 10.0.22621.1105Vendor says fixed in: not stated | |
| Microsoft Windows 8.1 | >= 6.3.0 and < 6.3.9600.20778Vendor says fixed in: not stated | |
| Microsoft Windows Server 2012 R2 | >= 6.3.9600.0 and < 6.3.9600.20778Vendor says fixed in: not stated | |
| Microsoft Windows Server 2012 R2 (Server Core installation) | >= 6.3.9600.0 and < 6.3.9600.20778Vendor says fixed in: not stated | |
| Microsoft Windows Server 2016 | >= 10.0.14393.0 and < 10.0.14393.5648Vendor says fixed in: not stated | |
| Microsoft Windows Server 2016 (Server Core installation) | >= 10.0.14393.0 and < 10.0.14393.5648Vendor says fixed in: not stated | |
| Microsoft Windows Server 2019 | >= 10.0.17763.0 and < 10.0.17763.3887Vendor says fixed in: not stated | |
| Microsoft Windows Server 2019 (Server Core installation) | >= 10.0.17763.0 and < 10.0.17763.3887Vendor says fixed in: not stated | |
| Microsoft Windows Server 2022 | >= 10.0.20348.0 and < 10.0.20348.1487Vendor says fixed in: not stated |
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.
Products named in our analysis
- microsoft:windows_10_1507
- microsoft:windows_10_1607
- microsoft:windows_10_1809
- microsoft:windows_10_20h2
- microsoft:windows_10_21h2
- microsoft:windows_10_22h2
- microsoft:windows_11_21h2
- microsoft:windows_11_22h2
- microsoft:windows_rt_8.1
- microsoft:windows_server_2012
- microsoft:windows_server_2016
- microsoft:windows_server_2019
- microsoft:windows_server_2022
Fix and mitigation
WAF and other mitigations
Can a WAF block it? No. The attack needs local access to the machine, so a WAF is not on its path.
Also consider: patch
Based on the attack vector (local or physical access). We check Cloudflare, AWS, Google Cloud Armor and Azure; for Akamai, Imperva, Fastly, F5, ask your vendor.
Remediation steps (AI-written)
Step-by-step remediation is generated for accounts on the Max plan, for CVEs that match a technology in their stack. Add this technology to your stack to see the fix checklist.
Exploitation evidence
- CISA KEV catalog
- Listed since 10 Jan 2023.
- CISA due date
- 31 Jan 2023, the remediation deadline for US federal agencies
- CISA required action
- Apply updates per vendor instructions.
- Public exploit code
- Unvetted proof-of-concept code on GitHub: 1 GitHub proof of concept
- CISA SSVC
- exploitation active, automatable no, technical impact totalAssessed by CISA 24 Jul 2024 (SSVC 2.0.3). Exploitation is none, poc (public proof of concept) or active.
GitHub proofs of concept
- hd3s5aa/CVE-2023-2167442 stars
Listed so you can judge urgency, not as a recommendation to run anything. GitHub “proofs of concept” are unvetted: some are fake or carry malware. Exploit-DB marks the entries its staff verified.
Timeline
- 10 Jan 2023Added to CISA KEV (exploited in the wild)
- 10 Jan 2023Published1 day later
- 31 Jan 2023CISA remediation due date (US federal agencies)20 days later
- 7 Mar 2024First proof-of-concept repository on GitHub (unvetted)401 days (about 1 year) later
- 24 Jul 2024CISA SSVC assessment: exploitation active140 days (about 5 months) later
- 21 Oct 2025CVE record last updated454 days (about 1 year) later
- 12 Nov 2026Analysed by vulneraibility.com387 days (about 1 year) later
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
| Metric | Value | What it means |
|---|---|---|
| Attack vector | LocalLocal access required (shell, logged-in user). | Local access required (shell, logged-in user). |
| Attack complexity | LowRepeatable attack, no special conditions. | Repeatable attack, no special conditions. |
| Privileges required | LowThe attacker needs basic user privileges. | The attacker needs basic user privileges. |
| User interaction | NoneNo victim action needed. | No victim action needed. |
| Scope | ChangedImpact crosses a security boundary into other components. | Impact crosses a security boundary into other components. |
| Confidentiality | HighTotal data disclosure possible. | Total data disclosure possible. |
| Integrity | HighComplete modification possible. | Complete modification possible. |
| Availability | HighFull outage possible. | Full outage possible. |
Common questions
Is CVE-2023-21674 being exploited?
Yes. CVE-2023-21674 appears in CISA's Known Exploited Vulnerabilities catalog, which means exploitation in the wild has been confirmed and reported. Treat it as active rather than theoretical, and patch it ahead of higher-scoring vulnerabilities that carry no exploitation evidence.
How severe is CVE-2023-21674?
CVE-2023-21674 is rated High with a CVSS score of 8.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2023-21674?
Yes. A fix has been recorded for CVE-2023-21674. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2023-21674 affect?
CVE-2023-21674 affects microsoft:windows_10_1507, microsoft:windows_10_1607, microsoft:windows_10_1809, microsoft:windows_10_20h2, and 9 further products or versions. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
References
2 references in the CVE record, grouped by the tags the record gives them.
Advisories (1)
- msrc.microsoft.com /update-guide/vulnerability/CVE-2023-21674
Other links (1)
- cisa.gov /known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-21674
Where the data on this page comes from
- CVE List (CVE.org): description, affected versions, references; CVE Terms of Use
- NVD: CVSS and CPE data
- CISA KEV catalog: exploitation, date added, due date
- CISA Vulnrichment (ADP): SSVC decision points
- FIRST EPSS: exploit probability and percentile
- PoC-in-GitHub: GitHub repositories that claim a proof of concept
Summary, impact and triage tags: written by our AI analysis pipeline from the sources above. Check them against the sources.
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