Umbraco 13 security support ends on 14 December 2026. Your website will not switch off on that date, but from then on any new security vulnerability discovered in Umbraco 13 will never be patched. Over time the risk compounds: attackers actively target CMS versions they know are unpatched, your hosting and insurance positions weaken, and anyone running security due diligence on your business will flag the site. The practical answer is to upgrade before the deadline. Our fixed price Umbraco 13 to 17 upgrade is £8,999 plus VAT and takes around 21 days end to end, so the work itself is quick. The risk is not the upgrade, it is leaving it until everyone else is booking the same work at once.
Out of support is one of those phrases that sounds administrative until you unpack it. Here is what actually changes on 14 December 2026, and what does not.
Your site does not stop working. Visitors will notice nothing on the day. This is exactly why so many businesses drift past the deadline: there is no immediate, visible consequence.
Umbraco stops issuing security patches for version 13. From that day, every newly discovered vulnerability in Umbraco 13 stays open forever. Attackers understand end-of-life calendars very well; unpatched CMS versions are among the easiest targets on the internet because the vulnerabilities are published and the fix will never come. The longer you run past the deadline, the larger the accumulated pile of unpatched issues becomes.
Even if you are never attacked, an unsupported CMS starts costing you elsewhere. Cyber insurance questionnaires ask directly about supported software. Enterprise customers running supplier due diligence will flag it. Developers become harder to hire for old versions, and every month on Umbraco 13 is a month of improvements you cannot easily make because nobody wants to build on a platform with a countdown on it.
Upgrade before the deadline, calmly, on your own schedule. Our fixed price Umbraco 13 to 17 upgrade is £8,999 plus VAT, takes around 21 days end to end, includes 30 days of cover after go live and has no downtime at cutover. We have taken sites through every major Umbraco version since v4, so this is routine work for us. The one thing we would say with urgency: capacity in the industry will tighten as December 2026 approaches, and planned upgrades are always cheaper than panicked ones. If you want to know exactly what your site needs, get in touch and we will tell you straight.
Tell us what you're working on and we'll come back within one working day.
An Umbraco Silver Partner agency in Llandudno, North Wales and the Isle of Man, building and looking after Umbraco and .NET websites for businesses and agencies across the UK and beyond. Simon Antony is a brand of Simplepage Ltd.
Maesgwyn, 3 Claremont rd,
Llandudno, North Wales, LL30 2UF