Microsoft will terminate all support for Windows 10 on October 14, 2025, leaving users with limited time to prepare. Despite the end-of-life (EOL) deadline already being very close, the market share of the decade-old operating system remains around 50%.
Defense contractors handling sensitive government data must understand that continuing operations on unsupported systems have serious consequences for their compliance with various Cybersecurity Maturity Model Certification (CMMC) requirements.
After October 14, 2025, Microsoft will cease providing any security updates, patches, or technical support for Windows 10. The operating system will continue working like before, but it won't evolve to address new security threats, compatibility requirements, or the changing technological landscape that emerges in the months and years ahead.
The first of these implications—zero protection against newly discovered vulnerabilities—is by far the biggest issue. Microsoft fixes around 1,000 Windows-related CVEs per year on average, including dozens of highly dangerous zero-day vulnerabilities.
Without patches, users will be exposed to every new exploit that hackers discover, which will turn their systems into easier and easier targets as time goes on. The FBI issued specific warnings about increased targeting of Windows 7 systems post-EOL, and security researchers expect similar campaigns against Windows 10 systems after October 2025.
The compatibility requirements create a second wave of problems that compound over time. As software vendors release updates designed for Windows 11's architecture and security features, Windows 10 systems become incompatible islands unable to run critical business applications.
The support of Microsoft 365 apps for Windows 10 ends simultaneously with the support of the operating system itself, meaning no new features, no performance optimizations, and no troubleshooting assistance. Defense contractors also rely on specialized software—CAD programs, project management platforms, communication tools—that will progressively abandon Windows 10 support and thus become impossible to update.
The changing technological landscape presents the third challenge: while Windows 10 remains frozen in 2025, the digital world accelerates forward. New encryption standards, authentication protocols, and security frameworks emerge constantly. Cloud services evolve their minimum requirements. Hardware manufacturers optimize drivers for current operating systems. Windows 10 becomes a time capsule, increasingly disconnected from modern infrastructure. It will be like using Internet Explorer in 2024—technically functional but practically obsolete. That's Windows 10's future trajectory post-support.
These cascading failures create consequences far beyond IT inconvenience. For defense contractors operating under strict regulatory frameworks like the CMMC, they translate directly into compliance violations that threaten their ability to bid on and maintain federal contracts.
Running Windows 10 after its end-of-life date directly violates multiple CMMC practices that are fundamental to maintaining certification:
The above-listed compliance failures reflect the reality of operating unprotected systems in today's threat landscape. Current data reveals that 60% of all data breaches result from unpatched vulnerabilities where fixes were available but not applied. Organizations running unpatched systems face 11.8% higher breach costs and require 12.8% longer to contain incidents. When you consider that average breach costs reached $4.88 million in 2024 and ransomware payments now average $417,410, the financial exposure from running unsupported Windows 10 dwarfs the upgrade costs across most small and midsize organizations.
The defense industrial base faces especially aggressive targeting from both nation-states and cybercriminals who understand the value of classified information and technical data. For example, recent breaches exposed 472 third-party credentials from six major contractors, including Lockheed Martin, BAE Systems, and Boeing.
Organizations can enroll in the Extended Security Updates (ESU) program as a temporary bridge. This program starts at $61 per device for year one, doubles to $122 in year two, and $244 in year three. So if there are, let's say, a hundred Windows 10 devices in your organization you would like to avoid updating for the next two years, the total cost of the ESU program for you would be $18,300.
The ESU program is a very expensive band-aid, and it doesn't even resolve CMMC compliance violations. The certification framework requires properly maintained and supported operating systems, period. You would be essentially paying thousands of dollars to remain non-compliant.
That's why it's best to update your devices to Windows 11 while there's still time to do so. Here's a quick roadmap that you can follow:
Automated discovery tools can be of great help when updating from Windows 10 to Windows 11 as they can quickly and reliably find every Windows 10 machine connected to the company network and automatically document hardware specs.
Once you've mapped your environment, run Microsoft's PC Health Check tool on every device to determine Windows 11 eligibility. Divide your systems into three categories:
Green Light Systems: Meet all Windows 11 requirements.
Yellow Light Systems: Could run Windows 11 with minor upgrades.
Red Light Systems: Unable to run Windows 11 due to fundamental limitations.
Working backward from October 14, 2025, you'll need to establish a realistic timeline that accounts for testing, procurement, deployment, and inevitable complications. Ideally, you should set your completion target for September 2025 so that you give yourself a month-long buffer before support ends for unexpected issues.
Start your deployment with high-priority machines across all three color categories (those handling CUI, running mission-critical applications, or serving key personnel) regardless of whether they need simple upgrades or full replacement. This way, your most important systems achieve compliance first, which gives you the best chance of avoiding issues with CMMC compliance.
For defense contractors, there's really only one viable path: complete migration before October 14, 2025. ESU might seem tempting for budget-constrained organizations, but it's a trap that leaves you non-compliant, increasingly vulnerable, and eventually facing the same migration at a higher cost. The question isn't whether to upgrade, but how quickly you can execute a comprehensive transition plan.
If your organization lacks the IT resources or expertise to complete the migration to Windows 11 in time, partnering with a managed service provider can be the difference between maintaining your CMMC certification and losing your ability to bid on federal contracts. At OSIBeyond, we specialize in helping defense contractors navigate complex IT transitions while maintaining continuous compliance. Our team can assess your current Windows 10 environment, develop a customized migration strategy, and execute the entire upgrade process.
Don't wait until it's too late; contact OSIBeyond today to discuss how we can help you meet the October 2025 deadline and keep your defense contracts secure.