Patch tracker / CVE reference / CVE-2026-21510
CVE-2026-21510
CVE-2026-21510 is a high severity Microsoft vulnerability with a CVSS score of 8.8. It is in the CISA Known Exploited Vulnerabilities catalog: attackers are using it in the wild, which makes it a fix-first item. Microsoft has shipped the fix: deploy one of the 14 updates below from the Microsoft Update Catalog, and see where this CVE sits against the rest on the patch tracker.
Risk summary
Listed in the CISA Known Exploited Vulnerabilities catalog, confirmed exploited in the wild. EPSS exploit probability 26%. CVSS 8.8 (High).
This CVE is among the lower half of tracked Microsoft CVEs by EPSS exploit probability, and one of 5 actively-exploited CVEs in February 2026.
This is a Windows Shell security feature bypass on the older Windows 10 1809 branch and Windows Server 2019, and CISA confirmed active exploitation by adding it to the KEV catalog on 2026-02-10. With a CVSS score of 8.8 High severity and a 26 percent EPSS probability, the confirmed in-the-wild use is the real driver here rather than the theoretical score. Anyone still running the 1809 servicing branch or Server 2019 is the exposed population.
Do this: Deploy the Microsoft patch for CVE-2026-21510 to all Windows 10 1809 and Windows Server 2019 systems now, prioritizing internet-facing and user-facing hosts to meet the KEV remediation timeline.
AI-generated from public data, 2026-07-21. Verify against the vendor advisory before acting.
Senserva AI Opinion and rich prompt for CVE-2026-21510
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Official patch(es) for CVE-2026-21510
Treat as urgent: it is being exploited in the wild (CISA KEV), so patch ahead of items that are not. In Intune or Defender, confirm whether the fixing updates KB5075897, KB5075899, KB5075904, KB5075906, KB5075912, KB5075941, KB5075942, KB5075943, KB5075970, KB5075971, KB5075999, KB5077179, KB5077181, KB5077212 are installed across the affected products. Senserva does this automatically across your tenant and flags every missing patch.
Apply the Microsoft security updates below to fix CVE-2026-21510. Each KB page carries the Microsoft Update Catalog download, Microsoft's known issues for the update, a copy-paste PowerShell check for whether it is installed, and the Senserva AI read.
Scope and sources
- Affected products
- Fixed by the same updates
- Authoritative references
Want every Microsoft CVE and the patches that fix it, ranked by real-world risk? See the Microsoft Patch Tracker.