Patch tracker / KB5120418
KB5120418: Windows Server 2016 Security Update (August 2026)
KB5120418 is a Critical security update for Windows Server 2016, released 2026-08-11. It closes 162 CVEs with a maximum CVSS of 9.8. At least one of them is actively exploited (CISA KEV), so it is urgent, and Microsoft lists 1 known issue: test it before broad deployment. The most likely of them to be attacked is CVE-2026-68820, which FIRST.org rates at 9% probability of exploitation in the next 30 days.
Before you deploy: Microsoft lists 1 known issue for this update.
Our data comes from Microsoft, CISA and other public sources, and it can be wrong or out of date. If you are unsure, check the linked source before you act, and tell us when we are wrong so we can fix it.
Update summary
Fixes 162 CVEs. At least one is actively exploited (CISA KEV). Most severe CVSS 9.8 (Critical). EPSS exploit probability up to 8.6%. Among the top half of tracked Microsoft updates by EPSS exploit probability.
A newer security update for Windows 10 Version 1607 for 32-bit Systems has shipped since this one: KB5126649 (2026-10-13). For cumulative update families the newer package includes these fixes, so installing that one is usually the shorter path. Verify against your own update rings before you skip this package.
Microsoft documents 1 known issue with this update.
- CompatTelRunner.exe might close unexpectedly
Senserva AI Opinion and rich prompt for KB5120418
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Full tracking and change history for KB5120418
- Released
- 2026-08-11
- Last changed
- 2026-10-30
- Changes tracked
- 10
Senserva began recording day-to-day change history on 2026-07-07, and refreshes it several times a day. Release dates are historical where Microsoft publishes them; revision history is tracked from that date forward, so it does not include changes made before then.
- 2026-08-12 CVEs fixed 168 to 169
- 2026-08-20 CVEs fixed 169 to 170
Recorded by Senserva on the dates shown, from the MSRC release feed. This is what moved and when, which neither the vendor advisory nor NVD publishes.
Check if KB5120418 is installed
Elevated PowerShell. No output means it is not installed.
Known issues, from Microsoft
Quoted from Microsoft's support article for KB5120418 (checked 2026-10-29). Microsoft lists 1 known issue. Verify against the article before acting.
CompatTelRunner.exe might close unexpectedly
Symptoms
After installing this update, some Windows Server 2016 devices might generate recurring Application Error events (Event ID 1000, with exception code 0xc0000409) associated with CompatTelRunner.exe. Reports have been observed on physical devices and virtual machines, including Azure and VMware environments.
CompatTelRunner.exe performs compatibility inventory and related diagnostic tasks. Although recurring CompatTelRunner.exe failures might generate Application event log entries, they do not affect device functionality. The associated event log warnings can be safely dismissed temporarily until a resolution is released in an upcoming update.
Resolution
This issue is resolved in Windows updates released on and after September 8, 2026 (such as KB5123099 ). We recommend you install the latest Windows update for your device as it contains important improvements and issue resolutions, including this one.
CVEs fixed by this update
Sorted exploited-first, then by CVSS. Every CVE links to its Senserva page with the full risk facts, references, and a ready-to-paste AI prompt.
Scope and sources
- Affected products
- Microsoft .NET Framework 3.5 AND 4.6.2/4.7/4.7.1/4.7.2 on Windows 10 Version 1607 for 32-bit Systems
- Microsoft .NET Framework 3.5 AND 4.6.2/4.7/4.7.1/4.7.2 on Windows 10 Version 1607 for x64-based Systems
- Microsoft .NET Framework 3.5 AND 4.6.2/4.7/4.7.1/4.7.2 on Windows Server 2016
- Microsoft .NET Framework 3.5 AND 4.6.2/4.7/4.7.1/4.7.2 on Windows Server 2016 (Server Core installation)
- Windows 10 Version 1607 for 32-bit Systems
- Windows 10 Version 1607 for x64-based Systems
- Windows Server 2016
- Windows Server 2016 (Server Core installation)
- Also released in August 2026
KB5120228
204 CVEs · Critical · exploitedKB5120229
184 CVEs · Critical · exploitedKB5120233
204 CVEs · Critical · exploitedKB5120238
174 CVEs · Critical · exploitedKB5120240
160 CVEs · Critical · exploitedKB5120242
184 CVEs · Critical · exploitedKB5120385
136 CVEs · Critical · exploitedKB5120386
131 CVEs · Critical · exploitedThe full month, summarized: Microsoft Patch Tuesday.
- Authoritative references
See this and every Microsoft update ranked by real-world risk on the Microsoft Patch Tracker.