Patch tracker / CVE reference / CVE-2026-49801
CVE-2026-49801
CVE-2026-49801 is a Microsoft vulnerability that Microsoft rates Important, with a CVSS score of 5.5 (Medium). Microsoft has shipped the fix: deploy one of the 9 updates below from the Microsoft Update Catalog, and see where this CVE sits against the rest on the patch tracker.
Risk summary
Not in the CISA KEV catalog. EPSS exploit probability 4.9%. CVSS 5.5 (Medium).
This CVE is among the top half of tracked Microsoft CVEs by EPSS exploit probability.
CVE-2026-49801 is an SMB information disclosure flaw rated Medium with a CVSS score of 5.5, affecting Windows 10 Version 1809 and Windows Server 2019. The SMB angle means an attacker who can reach the file sharing service could read memory contents they should not see, though it is not confirmed exploited and has no known ransomware use. The 1809 branch is old, so exposed machines here are often legacy systems that lag behind on patching.
Do this: Patch the affected 1809 and Server 2019 hosts, and confirm SMB is not reachable from untrusted networks in the meantime.
AI-generated from public data, 2026-07-21. Verify against the vendor advisory before acting.
Senserva AI Opinion and rich prompt for CVE-2026-49801
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Official patch(es) for CVE-2026-49801
Lower priority: patch in your normal cycle. In Intune or Defender, confirm whether the fixing updates KB5099444, KB5099445, KB5099535, KB5099536, KB5099538, KB5099539, KB5099540, KB5101649, KB5101650 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-2026-49801. 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
- Microsoft .NET Framework 3.5 AND 4.7.2 on Windows 10 Version 1607 for 32-bit Systems
- Microsoft .NET Framework 3.5 AND 4.7.2 on Windows 10 Version 1607 for x64-based Systems
- Microsoft .NET Framework 3.5 AND 4.7.2 on Windows Server 2016
- Microsoft .NET Framework 3.5 AND 4.7.2 on Windows Server 2016 (Server Core installation)
- Windows 10 Version 1607 for 32-bit Systems
- Windows 10 Version 1607 for x64-based Systems
- Windows 10 Version 1809 for 32-bit Systems
- Windows 10 Version 1809 for x64-based Systems
- Windows 10 Version 21H2 for 32-bit Systems
- Windows 10 Version 21H2 for ARM64-based Systems
- Windows 10 Version 21H2 for x64-based Systems
- Windows 10 Version 22H2 for 32-bit Systems
- Windows 10 Version 22H2 for ARM64-based Systems
- Windows 10 Version 22H2 for x64-based Systems
- Windows 11 Version 24H2 for ARM64-based Systems
- Windows 11 Version 24H2 for x64-based Systems
- Windows 11 Version 25H2 for ARM64-based Systems
- Windows 11 Version 25H2 for x64-based Systems
- Windows 11 Version 26H1 for ARM64-based Systems
- Windows 11 version 26H1 for x64-based Systems
- Windows Server 2012
- Windows Server 2012 (Server Core installation)
- Windows Server 2012 R2
- Windows Server 2012 R2 (Server Core installation)
- Windows Server 2016
- Windows Server 2016 (Server Core installation)
- Windows Server 2019
- Windows Server 2019 (Server Core installation)
- Windows Server 2022
- Windows Server 2022 (Server Core installation)
- Windows Server 2025
- Windows Server 2025 (Server Core installation)
- 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.