Patch tracker / CVE reference / CVE-2026-21247

CVE-2026-21247

High severity Microsoft vulnerability, CVSS 8.8. Fixed by 12 Microsoft security updates.

High

Risk summary

CVSS base
8.8
EPSS exploit probability
26%
Severity
High

Exploitation and severity

Not in the CISA KEV catalog. EPSS exploit probability 26%. CVSS 8.8 (High).

This CVE is among the lower half of tracked Microsoft CVEs by EPSS exploit probability.

What to do

Elevated priority: high severity or a meaningful exploitation probability, sooner if an affected product is internet-facing. In Intune or Defender, confirm whether the fixing updates KB5075897, KB5075899, KB5075904, KB5075906, KB5075912, KB5075941, KB5075942, KB5075943, KB5075999, KB5077179, KB5077181, KB5077212 are installed across the affected products. Senserva does this automatically across your tenant and flags every missing patch.

Official patch for CVE-2026-21247

Apply the Microsoft security updates below to fix CVE-2026-21247. Each KB page links to the Microsoft Update Catalog download for every affected product.

KB5075897KB5075899KB5075904KB5075906KB5075912KB5075941KB5075942KB5075943KB5075999KB5077179KB5077181KB5077212

Affected products

  • Windows 10 Version 1809 for 32-bit Systems
  • Windows 10 Version 1809 for x64-based Systems
  • Windows Server 2019

Authoritative references

NVD detailMicrosoft MSRCFIRST.org EPSS

Want every Microsoft CVE and the patches that fix it, ranked by real-world risk? See the Microsoft Patch Tracker.

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Lexicon: the terms on this page
CVE
Common Vulnerabilities and Exposures. A unique ID for one publicly known vulnerability, such as CVE-2025-1234.
KB
Microsoft Knowledge Base article. The identifier for a specific Microsoft update.
KEV
CISA Known Exploited Vulnerabilities. CVEs confirmed exploited in the wild. Fix these first.
CVSS
Common Vulnerability Scoring System. A standardized Severity score from 0 to 10.
EPSS
Exploit Prediction Scoring System. The probability a CVE will be exploited in the next 30 days.
MSRC
Microsoft Security Response Center. Microsoft's Patch Tuesday advisories and KB-to-CVE mapping.
NVD
National Vulnerability Database (NIST). Authoritative CVE metadata and CVSS scores.
Ransomware
The vulnerability is linked to known ransomware activity.