First release of the year — a broad spread across the Microsoft estate.
January 2026 set the tone with a wide-ranging release touching Windows, Office, Hyper-V and Azure components. Several rated Critical, with realistic exploitation paths for unmanaged endpoints.
- Risk theme: Hyper-V escape
- Risk theme: Windows TCP/IP RCE
- Risk theme: Office click-to-run flaw
- Risk theme: Azure Stack identity vulnerability
The issues that move the needle this month.
We have focused on the categories with realistic exploitation paths for UK SMEs and regulated firms. Always cross-check with Microsoft's Security Update Guide and your own asset inventory before deployment.
Hyper-V guest-to-host escape
A malicious VM could execute code on the host. Critical for organisations running shared virtualisation infrastructure.
Windows TCP/IP RCE
A flaw in TCP/IP processing could be exploited remotely against exposed Windows hosts. Reduces to a network-perimeter and segmentation conversation.
Office click-to-run RCE
A crafted document could execute code via the click-to-run service. Realistic phishing entry point.
Azure Stack identity vulnerability
Affects hybrid identity in Azure Stack deployments — relevant for the small subset of UK SMEs running on-premises Azure infrastructure.
Where the risk lives.
- — Windows 10, 11 and Server
- — Hyper-V hosts
- — Microsoft Office click-to-run installations
- — Azure Stack HCI / Hub
What to watch for when rolling out.
- Windows update temporarily affected VPN connectivity for a small number of third-party clients — vendor advisories followed within days.
- Office click-to-run update required a restart for the file association to update.
- Closes a broad set of issues early in the year — sets a clean baseline.
- Aligns well with new-year change-control windows.
- VPN regressions can affect remote workers if not validated.
- Larger update payload — bandwidth-sensitive for branch sites.
How experienced teams roll these out without drama.
- Validate VPN connectivity on a pilot group before broad rollout.
- Use a download distribution service (Connected Cache, WSUS, Intune delivery optimisation) to spare bandwidth.
- Refresh your asset inventory at the start of the year — patching only works on assets you know about.
Advice, guidance, or full remediation — your call.
Whether you want a second pair of eyes on this month's release or you would rather hand the entire patching cycle to us, Secure Chain Technology Group can support at any level of involvement.
- Advisory: a prioritised briefing mapped to your estate and risk appetite, with recommended rollout rings.
- Guided deployment: we work alongside your IT team — test plans, rollback procedures and change-management evidence.
- Fully managed remediation: we deploy, validate and report on every patch through our Vulnerability Management-as-a-Service (VMaaS) and Patch Management services.
- Compliance evidence: reporting aligned to Cyber Essentials Plus, ISO 27001 and DSPT requirements.
Always verify against the official Microsoft Security Update Guide and your own asset inventory before deployment.