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Exploited vulnerability · CISA KEV

Is CVE-2018-8639 exploited? Yes: in CISA KEV since 3 Mar 2025

Gociux · Microsoft Windows · data: CISA KEV, CVE record, FIRST EPSS

Yes. CVE-2018-8639, Microsoft Windows Win32k Improper Resource Shutdown or Release Vulnerability, is being exploited in the wild. CISA added it to its Known Exploited Vulnerabilities catalog on 3 Mar 2025, 2273 days after it was published. It is known to be used in ransomware campaigns. It affects Microsoft Windows. If you run it, CISA's required action is: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

exploitedYesCISA KEV · 3 Mar 2025
ransomwareKnownused in campaigns
EPSStop 5%very likely to be exploited
severity8.4CVSS 3.1 · high
US federal due24 Mar 2025BOD 22-01 deadline

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.

VendorMicrosoft (391 exploited CVEs in KEV)
ProductWindows
VulnerabilityMicrosoft Windows Win32k Improper Resource Shutdown or Release Vulnerability
WeaknessCWE-404
Published12 Dec 2018
Added to KEV3 Mar 2025
Reported by (CNA)microsoft

What to do

  1. Check whether you run it. Look for Windows in your asset inventory, including appliances and cloud images. Stack check lists every exploited Microsoft CVE at once.
  2. Apply the fix. Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
  3. If you can't patch today, take the affected service off the internet or restrict who can reach it, and check its logs for signs of compromise since 12 Dec 2018.
  4. Get told next time. Email alerts when CISA adds a CVE for Microsoft.

Other exploited CVEs in Windows

References

Questions

Is CVE-2018-8639 being exploited?

Yes. CISA added CVE-2018-8639 to the Known Exploited Vulnerabilities catalog on 3 Mar 2025, which means there is reliable evidence of exploitation in the wild.

Is CVE-2018-8639 used in ransomware attacks?

Yes, CISA lists it as known to be used in ransomware campaigns.

How do I fix CVE-2018-8639?

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. Check Microsoft's advisory for the fixed versions, and if you can't patch quickly, restrict access to the affected Windows and watch it for signs of compromise.

Sources: CISA KEV (exploitation, ransomware use, required action, due date), the CVE record (publication date, CVSS, CNA), NVD and FIRST EPSS (live score). More: all KEV additions in March 2025 · Microsoft scorecard · act-now radar.

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