# Microsoft Windows: Windows Win32k Improper Resource Shutdown or Release Vulnerability · pwn.watch

> Microsoft Windows Win32k contains an improper resource shutdown or release vulnerability that allows for local, authenticated privilege escalation. An attacker who successfully exploited this vulnerability could run arbitrary code in kernel mode. Added to CISA KEV on 2025-03-03.

Page: https://pwn.watch/i/microsoft-windows-cve-2018-8639 · generated 2026-10-23T03:01:01.167Z

## Status
- Severity: critical · status: closed · patch: patched
- Product: Microsoft Windows
- Started: 2025-03-03 · closed: 2025-03-03
- CVEs: CVE-2018-8639
- Affected: See vendor advisory / CISA notes (versions not always listed in KEV feed)
- Fixed in: See vendor advisory linked in sources

## Follow this incident
- RSS (one item per update): https://pwn.watch/i/microsoft-windows-cve-2018-8639/feed.xml
- JSON Feed: https://pwn.watch/i/microsoft-windows-cve-2018-8639/feed.json
- Full data (timeline, sources, posts, agentBrief): https://pwn.watch/i/microsoft-windows-cve-2018-8639.json
- This file: https://pwn.watch/i/microsoft-windows-cve-2018-8639/llms.txt

## Updates (newest first)
- 2025-03-03: CISA added CVE-2018-8639 to the KEV catalog (due 2025-03-24).

## Fix brief
# Security brief: Microsoft Windows: Windows Win32k Improper Resource Shutdown or Release Vulnerability

Source: https://pwn.watch/i/microsoft-windows-cve-2018-8639 · status: closed (closed Mar 3, 2025) · severity: critical · updated Mar 3, 2025

## Patch status
**PATCHED: fixed releases exist. Upgrade to a fixed version.**

## What it is
Microsoft Windows Win32k contains an improper resource shutdown or release vulnerability that allows for local, authenticated privilege escalation. An attacker who successfully exploited this vulnerability could run arbitrary code in kernel mode. Added to CISA KEV on 2025-03-03.

Severity detail: CVSS 8.4 (CISA ADP, v3.1); actively exploited (CISA KEV); known ransomware use

- Product: Microsoft Windows
- CVE / advisory ids: CVE-2018-8639

## Affected versions
- See vendor advisory / CISA notes (versions not always listed in KEV feed)

## Check whether you're affected
No generic command applies (the product is a hosted service, appliance or desktop app). Check the installed version in its admin UI / About screen and compare with the versions above.

## Fix
Upgrade to one of these fixed versions (or later on the same branch):
- See vendor advisory linked in sources

After upgrading, re-run the checks above and redeploy/restart the affected services.

## Latest updates
- Mar 3, 2025: CISA added CVE-2018-8639 to the KEV catalog (due 2025-03-24).

## Advisories
- [Microsoft advisory: Microsoft Windows](https://msrc.microsoft.com/update-guide/en-US/advisory/CVE-2018-8639) (Microsoft)
- [NVD: CVE-2018-8639](https://nvd.nist.gov/vuln/detail/CVE-2018-8639) (NVD)
- [CISA Known Exploited Vulnerabilities Catalog](https://www.cisa.gov/known-exploited-vulnerabilities-catalog) (CISA)

## Caveats
Derived from CISA KEV JSON feed catalogVersion 2026.10.21. CVSS from the CVE record (cvelistV5). Exact affected/fixed version strings are not always in the KEV record; verify against the vendor advisory URL. startedAt uses dateAdded (exploitation may have begun earlier; many entries are older CVEs newly confirmed as exploited in 2025).

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Machine-readable: https://pwn.watch/i/microsoft-windows-cve-2018-8639.json · all incidents: https://pwn.watch/incidents.json. Verify against the vendor advisory before changing production systems.