What does CMS end of life mean, and what should you do about it?
TL;DR
- CMS end of life means the vendor stops shipping security patches, bug fixes, and compatibility updates for that version. Your site keeps running, but nobody is maintaining it.
- Three deadlines worth knowing right now: Sitecore XP 10.3 mainstream support ended December 31, 2025, with the wider Sitecore Extended Support model moving to a paid model for security patches and incident support from June 1, 2026. Kentico 13 loses support in December 2026. Optimizely CMS 11 lost support on April 10, 2026, when CMS 13 shipped.
- Reaching end of life doesn't switch your site off. It does mean every future vulnerability, compliance question, and integration break is yours to fix alone, with no vendor patch coming.
- Starting a migration or upgrade plan 6-12 months ahead of a deadline gives you control over cost and timing. Waiting for an incident to force the decision doesn't.
CMS vendors retire old versions on a schedule, and most site owners find out their platform is on that schedule only when something breaks. If you're running Sitecore, Kentico, an older Optimizely CMS version, or any other platform with a defined support lifecycle, end of life is worth understanding before it becomes an emergency.
This guide covers what CMS end of life actually means, which platforms are hitting deadlines through 2026 and 2027, what it costs to ignore, and how to build a sunset plan instead of a scramble.
What "CMS end of life" actually means
End of life (EOL) is the point where a software vendor stops maintaining a specific version. It's not a judgment on your original platform choice. Every vendor does this, because supporting old code indefinitely slows down investment in the current product.
The support phases most vendors use
Most enterprise CMS vendors run a version through two or three phases before EOL:
- Mainstream support: full coverage. New features, bug fixes, security patches.
- Extended support: reduced coverage, usually critical bug fixes and security patches only, sometimes at extra cost.
- Sustaining or end of life: minimal to no support. Documentation and forums may remain, but patches stop.
Sitecore's own lifecycle follows this exact structure, and it's a useful reference for how these phases behave in practice, even if you're not on Sitecore.
What you actually lose
When a version hits end of life, the vendor stops providing:
- Security patches and vulnerability fixes
- Bug fixes and technical updates
- Compatibility updates as browsers, servers, and dependent frameworks move forward
- Official technical support
The site doesn't stop working. It gets frozen in time while everything around it, browsers, hosting infrastructure, third-party integrations, keeps changing. That gap is where the risk builds.
Note: end of life is not the same as an enforced shutdown. Optimizely, for example, states explicitly that it does not force upgrades, disable environments, or remove access to older CMS versions. Your site keeps running. What stops is the vendor watching for the next vulnerability on your behalf.
Which CMS platforms are hitting end of life in 2026 and 2027
If your organization runs Sitecore, Kentico, or Optimizely CMS, here's where things actually stand as of mid-2026.
Sitecore XP: extended support now comes at a cost
Sitecore XP 10.3 mainstream support ended December 31, 2025. Sitecore 9.0 reached full end of life the same day, and 9.1 has no security patches available at any price during its current Sustaining phase, which runs through December 31, 2026. Versions 9.2 and 9.3 are in Sustaining through December 31, 2027, meaning no security patches are available at any price, only paid production incident support.
The bigger shift lands June 1, 2026: Sitecore moves production incident support and security patches to a paid model across all versions still in Extended Support. Before that date, Extended Support included security patches as a baseline. After it, almost everything requires a separate paid arrangement.
Sitecore XP 10.4 is the exception with real runway: mainstream support through the end of 2027, extended support through 2030.
Kentico 13: the December 2026 deadline
Kentico 13 reaches end of life in December 2026, alongside older Kentico versions that are already unsupported. Once that window closes, Kentico 13 stops receiving security updates regardless of what vulnerabilities surface afterward.
Optimizely CMS 11: already out of support
Optimizely maintains only the two most recent major CMS versions at any time. CMS 13 reached general availability on March 31, 2026, and on April 10, 2026, Optimizely formally confirmed CMS 11 was out of support as a direct result. CMS 12 and CMS 13 are the currently maintained versions; CMS 11 and earlier no longer receive routine bug fixes, security monitoring, or patch releases, aside from severe security vulnerabilities raised by existing customers.
| Platform | Version | Status as of mid-2026 |
| Sitecore XP | 10.3 and earlier | Mainstream support ended Dec 31, 2025; Extended Support moves to a paid model for patches from June 1, 2026 |
| Sitecore XP | 10.4 | Mainstream support through end of 2027, extended through 2030 |
| Kentico | 13 and earlier | End of life December 2026 |
| Optimizely CMS | 11 and earlier | Out of support since April 10, 2026 |
| Optimizely CMS | 12, 13 | Currently maintained, actively patched |
If you're on Sitecore, niteco.com's Sitecore replatform service covers the full move to a currently supported platform. If you're on Kentico and evaluating whether to move to Xperience by Kentico or elsewhere, that's a separate conversation worth having early given the December 2026 date.
What running an unsupported CMS actually costs you
None of this is theoretical risk. It compounds in specific, predictable ways.
Security exposure that grows over time
Unpatched software is a known target. Once a version stops receiving fixes, any newly discovered vulnerability stays open indefinitely. Attackers actively scan for exactly this: unsupported platforms with public CVEs and no patch coming. The risk doesn't level off after EOL, it climbs, because more vulnerabilities get discovered over time and none of them get fixed.
Compliance and audit exposure
Running unsupported software can conflict with internal security policy, raise flags in vendor or customer audits, and complicate data protection compliance conversations, even before anything goes wrong. For regulated industries or B2B vendors who get assessed by their own customers' procurement teams, this shows up as a real blocker in deals, not just a hypothetical.
Rising cost of small changes
As dependencies age past what the vendor tests against, small changes take longer. Developers work around unsupported package versions, browser behavior the platform was never updated for, and integrations that quietly break when a third-party API changes on their end. The cost of maintaining the old platform tends to climb faster than the cost of a planned migration, just less visibly.
How to build a CMS sunset plan instead of a panic migration
The organizations that handle end of life well start planning before the deadline is close. That's the entire difference.
Audit your current platform and its real support window
Confirm your exact version and where it sits in the vendor's lifecycle. Don't assume "we're on the current version" without checking, particularly with Optimizely's two-version support policy or Sitecore's per-version dates. This step alone often surfaces a shorter runway than teams expect.
Decide: upgrade, migrate, or manage risk short term
Three real paths exist:
- Upgrade within the same platform if the vendor's newer version fits your needs and the upgrade path is well documented.
- Migrate to a different CMS if the platform itself is the problem, cost, flexibility, or vendor direction, not just the version.
- Short-term risk management (tighter monitoring, limited changes, custom patching) if you need a bridge before a bigger project, understanding this doesn't remove the underlying exposure.
For a deeper look at the trade-offs and common mistakes in that decision, see Niteco's guide to key considerations in replatforming.
Build a realistic timeline, not a rushed one
A migration touches content, design, integrations, and testing. Rushed migrations under deadline pressure are where SEO traffic gets lost, redirects get missed, and integrations break post-launch. Starting the conversation with a partner 6 to 12 months ahead of a hard deadline turns this into a planned project with a fixed scope, rather than a scramble against a support cutoff.
Tip: if your current deadline is more than a year out, that's still the right time to start scoping. Discovery, content audits, and vendor evaluation take real weeks even before development starts.
What a fixed-timeline replatform actually involves
For Sitecore-to-Optimizely moves specifically, Niteco runs this through an AI-assisted process called the Migration Machine. It scans the existing site and sitemap, classifies pages by template, builds the content model in Optimizely's Visual Builder, and migrates content page by page, including sliders, carousels, and other elements that plain text extraction tends to miss. Niteco reports this cuts migration time by up to 80% compared to a fully manual rebuild, and completed one client migration in 8 weeks.
Migrating off an end-of-life CMS? Niteco's replatform service runs on a fixed price and fixed 8-12 week timeline, with Core Web Vitals and SEO handled during the migration rather than after launch. See the replatform service details.
Niteco holds Optimizely's AI Innovator Partner of the Year (Asia-Pacific and Japan) award and reports over 2,000 Optimizely projects delivered and 222 Optimizely certifications across the team, alongside partner status with Contentful, Adobe, Kentico, and Umbraco for migrations off those platforms too.
What a replatform doesn't fix on its own
Moving off an end-of-life CMS removes the unsupported-software risk. It doesn't automatically fix a content model that was already disorganized, and it won't repair a weak content strategy that predates the migration. Skipping a content audit before migrating just moves the mess onto a newer, better-supported platform. If your current site has structural content problems, that's worth addressing as part of the same project, not something a new CMS solves by itself.
Similarly, a migration can preserve or even improve SEO performance with proper URL mapping and redirects, but it isn't automatic. It depends on the migration plan actually covering that work. Niteco's SEO migration checklist and introduction to Core Web Vitals cover what that involves in practice.
Conclusion
CMS end of life isn't an emergency on the day it happens, it's a slow-building risk that gets more expensive the longer it's ignored. If your platform is Sitecore XP 10.3 or earlier, Kentico 13, or Optimizely CMS 11, the support window is either closed or closing within months. The practical move is to get a fixed-scope migration or upgrade assessment now, while you still have time to plan it properly rather than react to it.
If your CMS is approaching or has reached end of life, start with an assessment of your current support risk, technical debt, integrations, and migration options. Planning early gives you more control over cost, timing, SEO protection, and platform choice.
FAQ
Your site keeps running. What stops is the vendor's security patching, bug fixes, and official support. Optimizely, for instance, states it doesn't disable environments or force upgrades, but any new vulnerability discovered after end of life goes unpatched indefinitely.
It depends on scope, but Niteco's replatform service runs on a fixed 8-12 week timeline for most projects, with proof-of-concept work available in as little as two weeks to validate the approach before committing to the full migration.
No. Sitecore XP 10.4 has mainstream support through the end of 2027 and extended support through 2030. The risk is specific to older versions: 10.3 and earlier have already lost mainstream support, and from June 1, 2026, security patches for any version still in Extended Support move to a paid model.
Upgrading moves you to a newer version of the same CMS, for example Optimizely CMS 11 to CMS 13. Migrating moves your site to a different CMS entirely, for example Sitecore to Optimizely. The right choice depends on whether the platform itself still fits your needs or just the version number is out of date.
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