# CVE-2018-8639: Microsoft Windows Win32k Improper Resource Shutdown or Release

> An attacker can exploit a Win32k memory handling flaw to gain elevated privileges on affected Windows systems.

- **Severity:** High 8.4 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Yes, since 3 Mar 2025 (CISA KEV), used in ransomware
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 12 Dec 2018
- **Updated:** 21 Oct 2025
- **Also known as:** GHSA-93mm-g479-2cx4

## What is CVE-2018-8639?

CVE-2018-8639 is a high-severity vulnerability in Microsoft Windows 10 1507, published on 12 Dec 2018. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

An elevation of privilege vulnerability exists in Windows when the Win32k component fails to properly handle objects in memory, aka "Win32k Elevation of Privilege Vulnerability." This affects Windows 7, Windows Server 2012 R2, Windows RT 8.1, Windows Server 2008, Windows Server 2019, Windows Server 2012, Windows 8.1, Windows Server 2016, Windows Server 2008 R2, Windows 10, Windows 10 Servers. This CVE ID is unique from CVE-2018-8641.

Weakness: CWE-404 (Improper Resource Shutdown or Release)

## Which versions are affected by CVE-2018-8639?

It affects 13 products.


Products: Microsoft Windows 10 1507, Microsoft Windows 10 1607, Microsoft Windows 10 1703, Microsoft Windows 10 1709, Microsoft Windows 10 1803, Microsoft Windows 10 1809, Microsoft Windows 7, Microsoft Windows 8.1, Microsoft Windows Rt 8.1, Microsoft Windows Server 2008, Microsoft Windows Server 2012, Microsoft Windows Server 2016, Microsoft Windows Server 2019.

## How do I fix CVE-2018-8639?

No fix has been published for CVE-2018-8639 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 24 Mar 2025.

## Is CVE-2018-8639 being exploited?

Yes. Attackers have exploited CVE-2018-8639 in the wild since at least 3 Mar 2025, including in ransomware campaigns.

Public exploit code:

- https://github.com/ze0r/CVE-2018-8639-exp (github_poc): https://github.com/ze0r/CVE-2018-8639-exp
- CVE-2018-8639-EXP (github_poc): https://github.com/timwhitez/CVE-2018-8639-EXP

## Other vulnerabilities in Microsoft Windows 10 1507

- [CVE-2017-8543](https://insights.sbomify.com/CVE-2017-8543/): Microsoft Windows Search Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2025-33053](https://insights.sbomify.com/CVE-2025-33053/): Microsoft Windows External Control of File Name or Path (high 8.8, exploited in the wild)
- [CVE-2025-33073](https://insights.sbomify.com/CVE-2025-33073/): Microsoft Windows SMB Client Improper Access Control (high 8.8, exploited in the wild)
- [CVE-2024-49039](https://insights.sbomify.com/CVE-2024-49039/): Microsoft Windows Task Scheduler Privilege Escalation (high 8.8, exploited in the wild)
- [CVE-2024-43461](https://insights.sbomify.com/CVE-2024-43461/): Microsoft Windows MSHTML Platform Spoofing (high 8.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-8639 and fix it if it is affected.

What it is: CVE-2018-8639 is a high-severity vulnerability in Microsoft Windows 10 1507, published on 12 Dec 2018. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: Yes. Attackers have exploited CVE-2018-8639 in the wild since at least 3 Mar 2025, including in ransomware campaigns.

Affected product: Microsoft Windows 10 1507. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2018-8639/ (Markdown: https://insights.sbomify.com/CVE-2018-8639/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-8639
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-8639
- OSV: https://osv.dev/vulnerability/CVE-2018-8639

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From sbomify Insights: https://insights.sbomify.com/CVE-2018-8639/
Summaries are generated and may contain mistakes; the official description above is the record.