Patch tracker / CVE reference / CVE-2026-21519
CVE-2026-21519
CVE-2026-21519 is a high severity Microsoft vulnerability with a CVSS score of 7.8. 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 12 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 7.8 (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.
CVE-2026-21519 is a Desktop Window Manager elevation of privilege flaw on Windows 10 Version 1809 and Windows Server 2019 that CISA confirmed as exploited and added to the KEV catalog on 2026-02-10. DWM runs as a core session component, so a local attacker who already has a foothold can use it to gain higher privileges on these older 1809 builds. With Severity rated High at CVSS 8.8 and an EPSS score of 26 percent, the confirmed in-the-wild exploitation is the reason to prioritize this over the raw probability.
Do this: Deploy the Microsoft patch for CVE-2026-21519 to all Windows 10 1809 and Windows Server 2019 systems now, prioritizing internet-facing and multi-user Server 2019 hosts.
AI-generated from public data, 2026-07-21. Verify against the vendor advisory before acting.
Senserva AI Opinion and rich prompt for CVE-2026-21519
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Official patch(es) for CVE-2026-21519
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, 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-2026-21519. 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.