Silverlight: no security updates since 2021

Social Housing · Cyber Essentials Plus · Civica Keystone

Keep Keystone running. Keep Cyber Essentials Plus. No rewrite.

Civica Keystone still runs on Microsoft Silverlight, and Silverlight stopped receiving security updates in 2021. That leaves housing associations and councils with two hard choices: a costly, multi-year migration, or an unsupported system sitting in the path of their next audit. Cloudhouse™ offers a third way. We isolate the Silverlight components so Keystone keeps working and stays out of Cyber Essentials Plus scope, with no code changes and results guaranteed.

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Keystone, on a supported estate Live

Windows 11 · Server 2022Fully patched and supported Patched

Isolated container

Silverlight componentsSealed off from the host OS Sealed

Cyber Essentials PlusSilverlight out of assessment scope Pass

2021

Year Microsoft ended support for Silverlight, the technology Keystone depends on

UK housing providers already kept live on Keystone by Cloudhouse, without a rewrite

Lines of application code changed, and no loss of Cyber Essentials Plus certification

The Keystone problem

A market-leading system, running on a dead browser plug-in.

Keystone manages assets, planned maintenance, servicing and compliance for a large share of UK social housing. It is business-critical, and for many teams it works well. The difficulty is underneath it: the browser interface runs on Microsoft Silverlight, which has had no security updates since 2021. That single dependency creates three separate pressures.

Compliance

Cyber Essentials Plus exposure

Unsupported software on an in-scope endpoint is exactly what a Cyber Essentials Plus assessor looks for. Many providers need the certification for government contracts and regulator confidence, and Silverlight puts it directly at risk.

Cost

The migration squeeze

The vendor route is to move onto a new cloud platform. That is a six-figure, multi-year programme with data migration, retraining and disruption to frontline services, on a timeline set by the supplier rather than by you.

Security

Risk that only grows

Every month an unpatched plug-in stays in production, the exposure widens. Doing nothing is not a neutral option, it is a decision to carry an increasing security and operational risk into the next audit cycle.

How Cloudhouse solves it

Isolate the risk. Keep the system. Keep the certification.

Cloudhouse containerises the legacy components at the application level. The Silverlight dependency is encapsulated inside a self-contained runtime and is never installed or registered on the host operating system. Keystone runs exactly as your teams know it, while the risky part is sealed away from everything around it.

01 / ISOLATE

Contain the Silverlight components

Legacy binaries packaged into an isolated runtime
Nothing unsupported installed on the host OS
The browser and Windows stay fully patched

02 / COMPLY

Take Keystone out of CE+ scope

Silverlight is not registered on the endpoint
Legacy code sits as encapsulated application libraries
Assessors see a supported, patched environment

03 / CONTINUE

Business as usual for your users

No rewrite and no code changes
No retraining, the interface is unchanged
Well-governed delivery through testing and go-live

The Cloudhouse approach

A proven, repeatable pattern, not a one-off fix.

Cloudhouse has been keeping business-critical Windows applications running safely on modern platforms since 2010. Keystone is one of the most common cases we see in social housing, and we have delivered the same containerisation approach across multiple associations and councils, each one keeping the system live and the certification intact.

Results guaranteed, or your money back

No source code, no vendor lock-in

Works for Keystone and the wider legacy Windows estate

Smooth, governed delivery across testing and go-live

Runs on current Windows 11 and Server 2022 or 2025

UK-based engineering and support

Book a 20-minute conversation See case studies

Your three options

Rewrite, risk it, or isolate it.

Every housing IT team facing Silverlight end of life is choosing between the same three paths. Set side by side, the trade-offs are clear.

	Migrate to a new platform	Carry on as-is	Cloudhouse
Cost and effort	Six-figure, multi-year programme	Low now, higher later	A fraction of a replacement, delivered in weeks
Disruption to services	Data migration and retraining	None until something breaks	None, the interface is unchanged
Cyber Essentials Plus	Resolved, eventually	At risk now	Protected, Silverlight out of scope
Who sets the timeline	The vendor	The next incident	You do

Proof from the sector

Housing teams who got ahead of it.

“Containerising the Silverlight components of Keystone through the Alchemy project with Cloudhouse was critical in allowing us to continue safely using the system. Isolating the components that posed a security risk removed our dependency on unsupported technology and kept Keystone running reliably and securely for our users. The project delivery was smooth, well-governed, and successful across testing and go-live, with support from the Cloudhouse team.”

Charlotte Sontag, ICT Solutions Architect, MHS Homes

Delivered across UK housing associations and councils

North Tyneside Council CHP Estuary MHS Homes

Get in touch

Silverlight won't fix itself. Let's talk before your next audit.

Tell us where the pressure is, an upcoming Cyber Essentials Plus assessment, a Keystone review, or a wider legacy Windows estate you need to modernise. We will show you the approach on your own system, not a generic demo.

Cyber Essentials Plus assessment coming up? We will show you how Keystone falls out of scope.
Being pushed toward a platform migration? We will map a way to defer it on your terms.
Other legacy Windows apps in the estate? We handle them the same way, one supplier.
Guaranteed delivery, so you can commit with confidence.

Our offices
Venture X · White City, London
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