Pantheon release notes

Pantheon will move all sites to the next-generation Global CDN, powered by Cloudflare. Upgrade your sites by March 31, 2027. Pantheon will migrate sites that you haven't self-upgraded by then, beginning in April 2027. Pantheon shares this early to give you time for this migration alongside other platform updates.

What you get

The next-generation Global CDN includes bot protection, on by default at no additional cost. Bot protection scores incoming traffic, challenges suspicious requests, and lets verified bots, such as search engine crawlers, through. The next-generation Global CDN also supports Multizone Failover, custom certificates, and platform vanity domains. Also new with the upgrade are Edge Traffic Visibility and Workspace Performance Insights.

Action required

Upgrade each site by March 31, 2027. Find the GCDN banner on the Site Dashboard and follow the migration instructions.

If your site uses a custom SSL certificate or a vanity domain, contact Support for assistance:

• For custom SSL certificates, Pantheon re-uploads your certificate to the new CDN before your domains move over.
• For vanity domains, Pantheon works with you to update your vanity domain's DNS during the migration.

Exceptions

This applies to every Pantheon site, with two exceptions:

1. Sites already on the next-generation Global CDN, including all sites created on or after September 10, 2026. Sites that still need to migrate show a GCDN banner on the Site Dashboard.
2. Sites that use Advanced Global CDN (AGCDN). Don't upgrade these yourself. Pantheon will contact you by December 15, 2026 to coordinate the migration. Wait for Pantheon's guidance before you take action. See the latest AGCDN migration release note for details.

If you don't take action

Pantheon will automatically migrate sandbox sites to the next-generation Global CDN by the end of 2026.

After the March 31, 2027 deadline, Pantheon will migrate any remaining sites. Pantheon will notify you at least 60 days before the scheduled migration. Upgrading yourself lets you choose when the change happens.

Need help?

• Review the next-generation Global CDN setup guide.
• Contact your Pantheon Customer Success Manager or account team.
• Open a support ticket from the Site Dashboard.

Editor's note (October 29, 2026): This release note was updated to add Edge Traffic Visibility and Workspace Performance Insights to the "What you get" section.

Moving forward, all Pantheon sites must be owned by a Professional Workspace. My Dashboard is not going away, but sites currently owned by an individual account must be moved. You can move your sites yourself now, before Pantheon begins migrating remaining sites in January 2027.

What you need to do

1. From My Dashboard, go to Sites and select the sites you want to transfer.
2. Select Move to workspace.
3. Choose the destination Professional Workspace and confirm the move.

The migration starts immediately, and you can move multiple sites at once. The migration will not affect your site's uptime or other site functionality; the primary change is where it appears in the Pantheon Dashboard.

Important

Self-service migration supports only unpaid Professional Workspaces. To move a site to a paid Professional Workspace, contact Pantheon Support.

Unpaid sites moved into an unpaid Professional Workspace will be subject to Pantheon's 30-day trial beginning in January 2027. Existing customers with active paid workspaces are not affected. Learn more about the 30-day trial.

If you don't take action

Starting in January 2027, Pantheon will automatically migrate sites still in My Dashboard into a system-generated Professional Workspace. Pantheon will notify you at least 30 days before migrating any of your sites.

The migration will not affect your site's uptime or other site functionality, but Pantheon will choose the destination workspace and its organization for you.

The latest security update for Next.js addresses three vulnerabilities in upstream dependencies: two critical vulnerabilities and one high-severity vulnerability.

Action required

Because this is a security update, we recommend that customers update affected Next.js applications as soon as possible. Customers are responsible for updating their application dependencies and redeploying; Pantheon does not update Next.js sites on customers' behalf.

The published Next.js advisory lists 16.4.1 and 15.5.28 as patched versions.

If your application directly manages React Server Components packages, update them to the patched versions listed in the React advisories: 19.0.9, 19.1.10, 19.2.9, or 19.3.1, as applicable.

Highlights

This update addresses three upstream security vulnerabilities:

• Critical — Remote code execution in image processing: A vulnerability in the upstream image-processing stack can lead to remote code execution when Next.js processes SVG files on glibc-based Linux systems. The advisory identifies Next.js 15.5.28 and 16.4.1 as patched versions. As a workaround, use Sharp 0.35.5 or later. See GHSA-2464-fhr4-w9xw.
• Critical — React Flight remote code execution: Crafted React Server Component payloads can lead to remote code execution in rare cases involving multiple typed arrays and attacker-controlled values. See GHSA-xqc2-xf4c-x3h3.
• High — Denial of service through Server Functions: Crafted requests to Server Function endpoints can cause excessive CPU use or out-of-memory exceptions. Applications that do not use server-side React or a framework that supports React Server Components are not affected. See GHSA-h3gv-c5rc-p453.

For full technical details and affected package versions, review the linked security advisories.

Pantheon is continuing the phased migration of Advanced Global CDN (AGCDN) to our next-generation edge platform. Starting October 15, 2026, AGCDN customers who use rate limiting or geolocation, and whose current configuration is fully supported in Phase 2, are eligible to migrate. Pantheon will contact eligible customers directly.

What's included

Phase 2 adds two features that you configure yourself in a pantheon-edge.yml file at the root of your site's code repository. Each site environment uses its own settings, and changes go live when you push and deploy your code. Changes no longer require a request to Pantheon.

• Rate limiting: Limit how many requests a single client, identified by IP address or JA4 fingerprint, can make to a site environment, using one of four pre-defined tiers.
• Geolocation: Send the visitor's approximate location, such as country, region, and city, to your site in a single Pantheon-Geo request header.

Before you migrate

• If your site reads AGCDN geolocation headers, update your code to read the Pantheon-Geo header. The header name, format, and available fields are different from AGCDN.
• Rate limiting uses pre-defined tiers. Custom request thresholds and time windows, including 1-second windows, aren't available.
• At launch, pantheon-edge.yml is supported for sites that push code to their Pantheon Git repository. Support for sites that use GitHub, GitLab, or Bitbucket integration, and for Next.js sites, is coming later.

How migration works

This migration is not self-serve. Pantheon's Professional Services team will:

1. Review your current Legacy AGCDN configuration and confirm feature support with current capabilities on NextGen.
2. Migrate your supported rules and configuration.
3. Make the migrated configuration available for you to review.
4. Coordinate the DNS cutover with you during an agreed change window.
5. Validate the configuration after cutover.

Action required

If you are eligible for Phase 2, you will receive an email. Respond to the ticket to confirm your technical contact so we can schedule your migration.

AGCDN customers who are not contacted for Phase 1 or Phase 2 don't need to do anything at this time, and will be contacted at a later date.

Learn how to configure rate limiting and geolocation in the Advanced Edge documentation. Learn more about our switch to Next-generation GCDN with bot protection in this related blog post.

Drupal core security release SA-CORE-2026-014 (CVE-2026-108097, risk 19/25) is now available. It fixes a critical remote code execution vulnerability in the Field UI module. Drupal core alone is not directly exploitable, but several exploit paths exist through contributed modules, and at least one does not require authentication. Custom code can also expose the vulnerable functionality.

Action required

Update your Drupal sites to a patched release as soon as possible.

• Drupal 11.4.10
• Drupal 11.3.19
• Drupal 10.6.19

Drupal 12.0.0-alpha1 through 12.0.0-beta1 are also affected. See the security advisory for Drupal 12 fix details.

Drupal 11.2.x and earlier, Drupal 10.5.x and earlier, Drupal 9, and Drupal 8.9 are end-of-life. They are affected and do not receive a patch. Upgrade these sites to a supported release.

Drupal 7 sites on Pantheon receive this fix through Drupal 7 long-term support. See the Drupal 7.107 release note.

To apply the update, use one-click core updates in the Pantheon dashboard.

Mitigation until you update

If you cannot update right away, uninstall the core Field UI module (field_ui). The Drupal Security Team states this protects your site until you update.

As a founding Platform Partner of the Drupal Steward program, Pantheon provides protection against some known attack vectors. Steward does not cover all possible exploits, so update your site.

As part of Pantheon's Long-Term Support (LTS) for Drupal 7, Drupal 7.107 is now available with a backported security patch.

This release backports the fix for SA-CORE-2026-014 (CVE-2026-108097), a critical remote code execution vulnerability in the Field UI module. Drupal core alone is not directly exploitable, but several exploit paths exist through contributed modules, and at least one does not require authentication.

Action required

Apply the latest upstream update to your Drupal 7 site to receive this fix. See related documentation for how to apply core updates.

This fix changes how Field UI overview tables assign rows to regions: Drupal core no longer calls the #region_callback function set on a table row. After you update, review whether any custom code uses #region_callback, and test the Manage fields and Manage display pages to confirm the Field UI tables work as expected.

About Drupal 7 long-term support

Pantheon has partnered with Tag1 Consulting to deliver security updates and maintenance for Drupal 7 sites. This extended support is included at no additional cost.

For configuration guidance and detailed information, visit our related documentation.

Pantheon's new product, P1, is now in Beta. P1 is Pantheon's AI-native web composition layer. It brings AI-assisted building, direct page editing, reusable components, and governed collaboration into one workflow—so teams can move faster without giving up standards, review, or control.

What's included in the Beta

The P1 Beta provides a foundation for teams that want to modernize how they create and manage web experiences.

• Visual, component-based page building with reusable components and templates.
• AI-assisted building and direct editing for marketers, editors, developers, and agents.
• Protected workstreams that let teams work in parallel while keeping the live site safe.
• Review, merge, publish, and revert workflows so teams can see what changed and approve consequential updates before they go live.
• Media management for the assets used in web experiences.
• A modern Next.js and React foundation that works alongside existing Pantheon workflows and connected systems.

P1 extends the systems and investments teams already rely on. It adds a creation and governance path without replacing existing WordPress, Drupal, or Next.js experiences.

Built for speed and control

P1 gives people and AI a shared environment to create, review, and evolve web experiences. Developers can establish reusable building blocks and guardrails, while marketers and editors can assemble and update pages directly within those standards.

Workstreams make parallel work visible and attributable. Teams can develop an initiative, review the proposed changes, compare them with the live experience, and merge approved work through a controlled path to production.

Beta access

P1 Beta access is limited and subject to review. The Beta is for organizations ready to work closely with Pantheon, launch a real website, and provide feedback as the product continues to mature.

What to expect during the Beta

P1 is usable for production implementations, but some capabilities, workflows, documentation, and implementation patterns may change during the Beta. Participants work closely with the P1 team and help shape improvements to the product and the implementation experience.

P1 Beta is an early step toward a broader release. Pantheon keeps adding capabilities and refining the experience based on customer feedback and real-world use.

Start building with P1

Visit p1.pantheon.io to learn more and request access. Use the P1 documentation when you are ready to explore the product. Read a blog post from Pantheon co-founder Josh Koenig on why Pantheon built P1.

Pantheon has updated the default PHP version for the Drupal (Composer Managed) upstream to PHP 8.3, replacing the previous default of PHP 8.2.

New Drupal sites created from Pantheon's upstreams use PHP 8.3. Existing sites that do not set php_version in their own pantheon.yml move to PHP 8.3 when they apply this upstream update. When you apply the update, Pantheon also updates config.platform.php in your composer.json to match, if it does not already.

Sites started from the Drupal 11 start state will see this update, but should already be running PHP 8.3.

Action required

Test the update before you deploy it to the Live environment. Apply it in Dev or a Multidev environment, confirm your modules and theme work on PHP 8.3, then promote it.

If your Drupal 10 site needs to stay on PHP 8.2, pin the version by setting php_version: 8.2 in your site's pantheon.yml before you apply the update. For steps, see Manage PHP Versions.

If you maintain a custom upstream, this change is not reflected in your pantheon.upstream.yml unless you update your fork from Pantheon's upstream.