Pantheon release notes

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.

The latest security release for WordPress, 7.1.3, is available on Pantheon.

Action required

Because this is a security update, we recommend all users upgrade to WordPress 7.1.3 as soon as possible from your Pantheon dashboard or Terminus to access the latest features, fixes, and security enhancements. See related documentation for how to apply core updates.

Pantheon has deployed a platform-wide mitigation (virtual patching via our routing network) against external abuse of the stored XSS on the Comments administration page, and is actively monitoring that rule. However, customers need to update their sites as soon as possible.

Highlights

This release resolves seven security vulnerabilities:

• A stored XSS on the Comments administration page, exploitable via pending comments.
• A DoS issue in the WP_Http::make_absolute_url() method.
• A second-order SQL injection in WordPress WXR export.
• A weakness allowing Author role users to sticky posts.
• Unauthenticated disclosure of comments on private and unpublished posts.
• Imgur embeds are vulnerable to XSS.
• Forgeable parameters passed to the {status}_{type} hook can lead to action name collision.

For full details, see the WordPress 7.1.3 release notes and WordPress documentation.

Pantheon is introducing the official Pantheon MCP Server, a governed way to let compatible AI agents operate on your Pantheon fleet through the platform API.

The MCP server exposes Pantheon operations as agent tools, mostly read-only, with any action that changes something requiring your approval in your AI client. It forwards the user's own Pantheon identity, so an agent can only reach what that user already can.

What's included

• A stateless MCP server that maps Pantheon operations to agent tools, covering workspaces, sites, environments, builds and deploy status, runtime logs, secrets, and upstreams, with no delete capabilities in this beta.
• Authorization stays with Pantheon: the server forwards the user's own token and the platform decides what that token may see and do.

Who it's for

Developers and teams using compatible AI coding agents who want to manage Pantheon sites and environments through agent workflows while keeping control of what agents can change.

How to get started

Connect from Claude Desktop, Web, or Code using the Pantheon MCP listing. Sign in with your normal Pantheon account through the OAuth flow; the client stores your token securely. Disconnect from the Pantheon MCP in the client to log out.

Support for more AI agents is coming soon.

For more details, see related documentation.

Availability

All Pantheon customers. For feedback, please sign up for the Pantheon Community Slack here if you don't already have an account and join us in the #beta-mcp-server channel.

Pantheon is opening the Beta of the Public API v1, a stable, Auth0-secured REST API for automating platform operations across your fleet.

The Public API v1 gives partners, DevOps teams, and agencies a documented, contract-stable way to run Pantheon operations programmatically. It extends the earlier alpha with expiring tokens and an OpenAPI 3.x schema that Pantheon commits to through GA.

What's included

• Auth0-secured authentication with expiration, replacing full-grant session tokens.
• Full operational surface: site, environment, backup, domain, and workflow operations.
• Initial capabilities: Upstream, Secrets Manager, access to Next.js build and runtime logs, and more.
• Published as an OpenAPI 3.x schema, so you can generate first-class clients directly.
• v1 contract stability, committed through GA.

Who it's for

Technology partners embedding Pantheon in their own products, enterprise DevOps teams standardizing across many sites, agencies building client dashboards, and regulated-industry customers who require expiring tokens.

How to get started

The API is served at api.pantheon.io under /v1. Interactive docs are at /docs and the OpenAPI spec at /v1/openapi.json. Authenticate with your own Auth0-issued token.

For more details, see related documentation.

Alpha (v0) users

The v0 API keeps running for about 60 days after today's Beta release of v1, then shuts down. The /v1 endpoints reject legacy machine tokens, so move to personal access tokens.

Availability

All Pantheon customers. For feedback, please sign up for the Pantheon Community Slack here if you don't already have an account and join us in the #beta-public-api channel.