In short: A corporate IT environment is no longer limited to a single operating system. Windows now coexists with macOS, Linux servers, and virtualized environments, and each of these systems faces its own set of critical vulnerabilities—sometimes within the same week. Hardening only Windows is tantamount to leaving part of the IT environment defenseless. Hardening must therefore be multi-OS to cover the actual attack surface.

A hardening tool that covers only a single operating system protects only a fraction of your IT infrastructure. In July 2026, CERT-FR published critical privilege escalation vulnerabilities for Windows (CERTFR-2026-AVI-0895) and for the Linux kernel (CVE-2026-46242, known as “Bad Epoll”) in the same week—concrete proof that the threat knows no boundaries between operating systems. Given that device fleets have become highly heterogeneous, endpoint hardening must be applied consistently to Windows, Linux, and macOS under a single compliance framework. This article explains why and how.

Why don't companies use a single operating system for their IT infrastructure anymore?

The “all-Windows” desktop is a thing of the past. Operating system market share figures confirm this: in June 2026, StatCounter reported desktop market shares of 62.16% for Windows, 14.58% for macOS, and 3.09% for Linux, with the remainder partially obscured by privacy tools. In other words, nearly one in five computers worldwide is no longer running Windows—a proportion that is even higher in the United States, where macOS accounts for over 30% of the desktop market.

In the enterprise sector, the shift is even more pronounced. According to Jamf’s adoption research, Macs now account for about 27% of the device fleet in the organizations surveyed. 93% of CIOs surveyed report an increase in the use of Apple devices over the past two years, and 96% consider Apple technologies to be important to their IT strategy. Mac shipments rose 17.3% year-over-year in the fourth quarter of 2024. The reasons are well known: employee preference, choices made by development and management teams, and the rise of BYOD and hybrid work.

On the server and cloud side, Linux is no longer the exception but the norm. Linux powers approximately 51.3% of server operating systems in 2026 (up from 44.8% in 2024), 90% of public cloud workloads, and 96% of production Kubernetes clusters run on a Linux node OS. As a result, as soon as an SMB or mid-sized company has servers, cloud resources, a development team, or a few Macs, it is effectively operating a multi-OS environment. The question is no longer “Do we have multiple operating systems?” but “Have we hardened them all to the same level?”

The threat doesn't stop at Windows

For a long time, the idea that macOS and Linux were “naturally secure” served as a justification for hardening only Windows. That belief has now been disproved by the facts. The news from the week of July 14–21, 2026, provides a telling example: CERT-FR issued a series of advisories regarding Windows vulnerabilities that allow remote code execution and privilege escalation (CERTFR-2026-AVI-0895), and its news bulletin highlighted “Bad Epoll ” (CVE-2026-46242), a Linux kernel flaw allowing a local, unprivileged attacker to elevate privileges, with a public proof-of-concept. That same week, a researcher documented “Januscape” (CVE-2026-53359), a guest-to-host escape on KVM hypervisors. Three families of systems, three critical vulnerabilities, all in a single week.

Threat statistics confirm the underlying trend for macOS. Malware incidents targeting macOS increased by 73% between 2024 and 2025. In 2025, 66% of Mac users encountered a cyberthreat, and backdoor-type malware increased by 67%. Analyses by Jamf Threat Labs identified more than 26,000 variants of macOS malware in 2025 alone and found that 44% of the devices examined were affected by malicious network traffic. The increasing professionalization of cybercrime (the Malware-as-a-Service model, subscription-based infostealers) makes macOS just as lucrative a target as any other. The conclusion shared by analysts is unambiguous: the myth of macOS’s immunity has definitively come to an end.

A single unhardened post puts the rest of the fleet at risk

The risk posed by a partially compromised environment is not just a local one. A compromised Mac or Linux server becomes a foothold for lateral movement toward Windows workstations, SaaS applications, and data in the cloud. An endpoint that sends malicious attachments, syncs infected files to shared storage, or exposes credentials that are reused elsewhere turns an isolated incident into a compromise of the entire system. The security of a minority OS in the IT environment is therefore not a “Mac issue” or a “Linux issue”—it’s an enterprise-wide issue, because the weakest link determines the actual level of protection.

How can you strengthen a diverse workforce without increasing the number of tools?

The answer can be summed up in one word: consistency in control, not an increase in the number of consoles. Managing a separate hardening tool for Windows, one for macOS, and one for Linux leads to duplicate licenses, an increased administrative burden, and—most importantly—inconsistent enforcement of security policies, resulting in “policy drift,” friction during audits, and slower incident response. The key indicator—as emphasized by experts in heterogeneous fleet management—is not whether each platform has “its own” tool, but whether a single control model produces the same result across every class of device.

In practical terms, consistent multi-OS hardening rests on three pillars. First, recognized, cross-platform standards: the CIS Benchmarks are available for Windows, macOS, and major Linux distributions, and the ANSSI hardening guides (ANSSI-BP-028 series) cover both GNU/Linux and Windows. Building on these foundations ensures a common compliance framework. Second, continuous verification of the actual status of each workstation—rather than simply confirming that a command has been accepted—to detect discrepancies on any OS. Finally, automated remediation that applies priority measures (disabling unnecessary services, restricting privileges, enabling native audit logs such as `auditd` on Linux or advanced audit policies on Windows) without requiring a complete overhaul of the IT infrastructure.

This approach directly addresses compliance requirements, which also make no distinction between operating systems. NIS2, DORA, and ISO 27001 require control over the security configuration of all systems within the scope. A compliance dashboard that excludes 20 to 30% of the device fleet—the portion running macOS and Linux—cannot provide comprehensive audit evidence.

Key Takeaways

The heterogeneity of IT environments is not a passing trend but a structural reality: Windows still dominates the desktop, but macOS is becoming firmly established in the enterprise, and Linux reigns supreme on servers and in the cloud. Attackers are keeping pace with this diversification, as evidenced by both threat statistics and weekly vulnerability reports. Securing an IT environment therefore requires applying the same level of rigor to every operating system, based on common standards (CIS, ANSSI) and a unified control model—otherwise, the attack surface that is actually protected remains incomplete.

FAQ

Does a predominantly Windows environment really need multi-OS hardening?

Yes. Even with a majority of Windows workstations, the presence of a few Macs (often used by executives or developers with privileged access) and Linux servers is enough to create blind spots. A single unhardened endpoint can serve as an entry point to compromise the entire network through lateral movement.

Is macOS really a target of cyberattacks?

Yes. Incidents of macOS malware increased by 73% between 2024 and 2025, and 66% of Mac users encountered a threat in 2025, according to industry threat reports. Apple’s built-in protections (Gatekeeper, SIP, TCC) are helpful but are no substitute for security hardening that is configured and continuously monitored.

What standards should be used to harden multiple operating systems in a consistent manner?

CIS Benchmarks provide baselines for Windows, macOS, and major Linux distributions. In France, the ANSSI hardening guidelines (ANSSI-BP-028) cover GNU/Linux and Windows. Using these recognized standards allows you to document the same compliance requirements across your entire IT infrastructure, which is what NIS2, DORA, and ISO 27001 auditors expect.

Do you need a different tool for each operating system?

This is neither necessary nor recommended. Using multiple consoles results in duplicate licenses, increased administrative overhead, and inconsistent policy enforcement. The goal is a unified control model capable of achieving the same compliance outcome on Windows, macOS, and Linux.

In what ways do NIS2 or DORA compliance requirements mandate multi-OS coverage?

These regulations require full control over the security configuration of all systems within the perimeter, regardless of the operating system. A dashboard that covers only Windows leaves macOS and Linux without proof of compliance, which weakens the audit and risk analysis.

Sources

How long does it take to bring a heterogeneous fleet—Windows, Linux, and macOS—into compliance with CIS or ANSSI standards? Cyberlib automates the hardening of your endpoints, regardless of their operating system, with continuous compliance monitoring and remediation without the need to overhaul your fleet, all from a single console. Learn how to harden your entire fleet.